Articulation Systems, Devices, and Methods for Catheters and Other Uses

ABSTRACT

Articulation devices, systems, methods for articulation, and methods for fabricating articulation structures will often include simple balloon arrays, with inflation of the balloons interacting with elongate skeletal support structures so as to locally alter articulation of the skeleton. The balloons can be mounted to a substrate of the array, with the substrate having channels that can direct inflation fluid to a subset of the balloons. The articulation array structure may be formed using simple planar 3-D printing, extrusion, and/or laser micromachining techniques. The skeleton may comprise a simple helical coil or interlocking helical channels, and the array can be used to locally deflect or elongate an axis of the coil under control of a processor. Liquid inflation fluid may be directed to the balloons from an inflation fluid canister, and may vaporize within the channels or balloons of the articulation system, with the inflation system preferably including valves controlled by the processor. The articulation structures can be employed in minimally invasive medical catheter systems, and also for industrial robotics, for supporting imaging systems, for entertainment and consumer products, and the like.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority from co-assignedU.S. Provisional Patent App. Nos. 62/139,430 filed Mar. 27, 2015,entitled “Articulation System for Catheters and Other Uses” (AttorneyDocket No. 097805-000100US-0939456); 62/175,095 filed Jun. 12, 2015,entitled “Selective Stiffening for Catheters and Other Uses” (AttorneyDocket No. 097805-000110US-0941721); 62/248,573 filed Oct. 30, 2015,entitled “Fluid Articulation for Catheters and Other Uses” (AttorneyDocket No. 097805-000120US-0962383); 62/263,231 filed Dec. 4, 2015,entitled “Input and Articulation System for Catheters and Other Uses”(Attorney Docket No. 097805-000200US-0966468); and 62/296,409 filed onFeb. 17, 2016, entitled “Local Contraction of Flexible Bodies usingBalloon Expansion for Extension-Contraction Catheter Articulation andOther Uses” (Attorney Docket No. 097805-000300US-0970626); the fulldisclosures which are incorporated herein by reference in their entiretyfor all purposes.

The subject matter of the present application is related to that ofco-assigned U.S. patent application Ser. No. ______ filed concurrentlyherewith, entitled “Fluid Drive System for Catheter Articulation andOther Uses” (Attorney Docket No. 097805-000140US-0970629), and ______also filed concurrently herewith, entitled “Fluid-Expandable BodyArticulation of Catheters and Other Flexible Structures” (AttorneyDocket No. 097805-000150US-0970627); the full disclosures which are alsoincorporated herein by reference in their entirety for all purposes.

FIELD OF THE INVENTION

In general, the present invention provides structures, systems, andmethods for selectively bending or otherwise altering the bendcharacteristics of catheters and other elongate flexible bodies, thelengths of such bodies, and the like. Embodiments of the invention maybe used to reversibly, locally, and/or globally alter the stiffness(such as to stiffen or reduce the stiffness of) elongate flexible bodiesused for medical and other applications. The invention may include or beused with articulation structures, systems, and methods forarticulation, as well as for controlling and fabricating articulationstructures. In exemplary embodiments the invention provides articulatedmedical systems having a fluid-driven balloon array that can help shape,steer and/or advance a catheter, guidewire, or other elongate flexiblestructure along a body lumen. Also provided are structures forfacilitating access to and/or alignment of medical diagnostic andtreatment tools with target tissues, articulation fluid control systems,and medical diagnostic and treatment related methods. Alternativeembodiments make use of balloon arrays for articulating (or altering thestiffness of) flexible manipulators and/or end effectors, industrialrobots, borescopes, prosthetic fingers, robotic arms, positioningsupports or legs, consumer products, or the like.

BACKGROUND OF THE INVENTION

Diagnosing and treating disease often involve accessing internal tissuesof the human body. Once the tissues have been accessed, medicaltechnology offers a wide range of diagnostic tools to evaluate tissuesand identify lesions or disease states. Similarly, a number oftherapeutic tools have been developed that can help surgeons interactwith, remodel, deliver drugs to, or remove tissues associated with adisease state so as to improve the health and quality of life of thepatient. Unfortunately, gaining access to and aligning tools with theappropriate internal tissues for evaluation or treatment can represent asignificant challenge to the physician, can cause serious pain to thepatient, and may (at least in the near term) be seriously detrimental tothe patient's health.

Open surgery is often the most straightforward approach for gainingaccess to internal tissues. Open surgery can provide such access byincising and displacing overlying tissues so as to allow the surgeon tomanually interact with the target internal tissue structures of thebody. This standard approach often makes use of simple, hand-held toolssuch as scalpels, clamps, sutures, and the like. Open surgery remains,for many conditions, a preferred approach. Although open surgicaltechniques have been highly successful, they can impose significanttrauma to collateral tissues, with much of that trauma being associatedwith gaining access to the tissues to be treated.

To help avoid the trauma associated with open surgery, a number ofminimally invasive surgical access and treatment technologies have beendeveloped. Many minimally invasive techniques involve accessing thevasculature, often through the skin of the thigh, neck, or arm. One ormore elongate flexible catheter structures can then be advanced alongthe network of blood vessel lumens extending throughout the body and itsorgans. While generally limiting trauma to the patient, catheter-basedendoluminal therapies are often reliant on a number of specializedcatheter manipulation techniques to safely and accurately gain access toa target region, to position a particular catheter-based tool inalignment with a particular target tissue, and/or to activate or use thetool. In fact, some endoluminal techniques that are relatively simple inconcept can be very challenging (or even impossible) in practice(depending on the anatomy of a particular patient and the skill of aparticular physician). More specifically, advancing a flexible guidewireand/or catheter through a tortuously branched network of body lumensmight be compared to pushing a rope. As the flexible elongate bodyadvances around first one curve and then another, and through a seriesof branch intersections, the catheter/tissue forces, resilient energystorage (by the tissue and the elongate body), and movement interactionsmay become more complex and unpredictable, and control over therotational and axial position of the distal end of a catheter can becomemore challenging and less precise. Hence, accurately aligning theseelongate flexible devices with the desired luminal pathway and targettissues can be a significant challenge.

A variety of mechanisms can be employed to steer or variably alterdeflection of a tip of a guidewire or catheter in one or more lateraldirections to facilitate endoluminal and other minimally invasivetechniques. Pull wires may be the most common catheter tip deflectionstructures and work well for many catheter systems by, for example,controllably decreasing separation between loops along one side of ahelical coil, braid, or cut hypotube near the end of a catheter or wire.It is often desirable to provide positive deflection in opposeddirections (generally by including opposed pull wires), and in manycases along two orthogonal lateral axes (so that three or four pullwires are included in some devices). Where additional steeringcapabilities are desired in a single device, still more pull wires maybe included. Complex and specialized catheter systems having dozens ofpull wires have been proposed and built, in some cases with each pullwire being articulated by a dedicated motor attached to the proximalend. Alternative articulation systems have also been proposed, includingelectrically actuated shape memory alloy structures, piezoelectricactuation, phase change actuation, and the like. As the capabilities ofsteerable systems increase, the range of therapies that can use thesetechnologies should continue to expand.

Unfortunately, as articulation systems for catheters get more complex,it can be more and more challenging to maintain accurate control overthese flexible bodies. For example, pull wires that pass through bentflexible catheters often slide around the bends over surfaces within thecatheter, with the sliding interaction extending around not only bendsintentionally commanded by the user, but also around bends that areimposed by the tissues surrounding the catheter. Hysteresis and frictionof a pull-wire system may vary significantly with that slidinginteraction and with different overall configurations of the bends, sothat the articulation system response may be difficult to predict andcontrol. Furthermore, more complex pull wire systems may add additionalchallenges. While opposed pull-wires can each be used to bend a catheterin opposite directions from a generally straight configuration, attemptsto use both together—while tissues along the segment are applyingunknown forces in unknown directions—may lead to widely inconsistentresults. Hence, there could be benefits to providing more accurate smalland precise motions, to improving the lag time, and/or to providingimproved transmission of motion over known catheter pull-wire systems soas to avoid compromising the coordination, as experienced by thesurgeon, between the input and output of catheters and other elongateflexible tools.

Along with catheter-based therapies, a number of additional minimallyinvasive surgical technologies have been developed to help treatinternal tissues while avoiding at least some of the trauma associatedwith open surgery. Among the most impressive of these technologies isrobotic surgery. Robotic surgeries often involve inserting one end of anelongate rigid shaft into a patient, and moving the other end with acomputer-controlled robotic linkage so that the shaft pivots about aminimally invasive aperture. Surgical tools can be mounted on the distalends of the shafts so that they move within the body, and the surgeoncan remotely position and manipulate these tools by moving input deviceswith reference to an image captured by a camera from within the sameworkspace, thereby allowing precisely scaled micro-surgery. Alternativerobotic systems have also been proposed for manipulation of the proximalend of flexible catheter bodies from outside the patient so as toposition distal treatment tools. These attempts to provide automatedcatheter control have met with challenges, which may be in-part becauseof the difficulties in providing accurate control at the distal end of aflexible elongate body using pull-wires extending along bending bodylumens. Still further alternative catheter control systems apply largemagnetic fields using coils outside the patient's body to directcatheters inside the heart of the patient, and more recent proposalsseek to combine magnetic and robotic catheter control techniques. Whilethe potential improvements to control surgical accuracy make all ofthese efforts alluring, the capital equipment costs and overall burdento the healthcare system of these large, specialized systems is aconcern.

In light of the above, it would be beneficial to provide improvedarticulation systems and devices, methods of articulation, and methodsfor making articulation structures. Improved techniques for controllingthe flexibility of elongate structures (articulated or non-articulated)would also be beneficial. It would be particularly beneficial if thesenew technologies were suitable to provide therapeutically effectivecontrol over movement of a distal end of a flexible guidewire, catheter,or other elongate body extending into a patient body. It would also bebeneficial if the movement provided by these new techniques would allowenhanced ease of use; so as to facilitate safe and effective access totarget regions within a patient body and help achieve desired alignmentof a therapeutic or diagnostic tool with a target tissue. It would alsobe helpful if these techniques could provide motion capabilities thatcould be tailored to at least some (and ideally a wide) range ofdistinct devices.

In light of the above, it would also be beneficial to provide new andimproved devices, system, and methods for driving elongate flexiblestructures. It would also be beneficial to provide improved medicaldevices, systems, and methods, particularly those that involve the useof elongate flexible bodies such as catheters, guidewires, and otherflexible minimally invasive surgical tools. It would be desirable totake advantage of recent advances in microfluidic technologies andfabrication techniques to provide fluid drive systems having arelatively large number of fluid channels that could be used to controlcatheters and other elongate flexible structures within a patient, orthat could otherwise be used to accurately control flow to and/or withina multi-lumenal shaft, ideally without having to resort to large,expensive systems having large numbers of motors or the like.

In light of the above, it would further be beneficial to provide new andimproved articulation devices, system, and methods for use with elongateflexible structures. It would also be beneficial to provide improvedmedical devices, systems, and methods, particularly those that involvethe use of elongate flexible bodies such as catheters, guidewires, andother flexible minimally invasive surgical tools. It would be desirableif these improved technologies could offer improved controllability overthe resting or nominal shape of a skeleton of a flexible body, and stillallow the overall body to bend (safely and predictably) against softtissues, ideally without requiring the use of very expensive components,large numbers of parts, and/or exotic materials.

BRIEF SUMMARY OF THE INVENTION

The present invention generally provides articulation devices, systems,methods for articulation, along with methods for fabricatingarticulation structures. The articulations structures described hereinwill often include simple balloon arrays, with inflation of the balloonsinteracting with elongate skeletal support structures so as to locallyalter articulation of the skeleton. The balloons can be supported by asubstrate of the array, with the substrate having channels that candirect inflation fluid to a subset of the balloons. The articulationarray structure may be formed using extrusion, planar 3-D printing,and/or laser micromachining techniques. The skeleton may compriseinterlocking helical channels, a simple helical coil, or a printedtubular structure, and the array can be used to locally deflect orelongate an axis of the frame under control of a processor. Liquidinflation fluid may be directed toward the balloons from an inflationfluid canister, and may vaporize within the channels or balloons of thearticulation system, with the inflation system preferably includingvalves controlled by the processor. A flexible vacuum chambersurrounding the balloons may ensure fluid integrity. The articulationstructures can be employed in minimally invasive medical cathetersystems, and also for industrial robotics, for supporting image capturedevices, for entertainment and consumer products, and the like.

In a first aspect, the invention provides an articulatable systemcomprising an elongate flexible body having a proximal end and a distalend with an axis therebetween. A plurality of balloons is disposed alongthe flexible body, and inflation of the balloons from a firstconfiguration to a second configuration during use alters a bendcharacteristic of the elongate body. A fluid source can be coupled withthe flexible body so as to transmit liquid from the source toward theflexible body. The liquid vaporizes to an inflation gas during use suchthat the balloons in the second configuration are inflated by theinflation gas.

In many embodiments, the elongate body comprises a catheter body. Anumber of features may, independently or in combination, enhance thesafe and accurate use of such catheters. The catheter body can include askeleton having pairs of interface regions with offsets therebetween,the balloons typically being disposed between the interface regions ofthe pairs. Preferably, the skeleton comprises a helical member, theballoons being supported by the member and the offsets between theinterface pairs extending primarily axially and anglingcircumferentially, often in correlation with a pitch of the helicalmember. Advantageously, a sheath can be sealed around the balloons so asto form a pressure chamber (ideally in the form of a vacuum chamber).The chamber can be operatively coupled to a fluid source so as toinhibit transmission of the liquid from the source in response todeterioration of a vacuum within the chamber. Typically, the balloonsare included in an array of balloons and are mounted to a substrate. Thesubstrate can have channels providing fluid communication between thefluid source and the balloons. The substrate can optionally comprise amulti-lumen shaft, with some substrate shafts being helical, and othersextending coaxially with the frame.

As one of a number of features (that are not tied to any specificembodiment), the fluid source will often include a canister, theexemplary canister being a single-use canister having a frangible seal,preferably containing less than 10 oz. of the liquid (and often lessthan 5 oz., with many containing less than 1 oz). The liquid oftencomprises a relatively benign cryogen such as N2O. The liquid can bedisposed in the canister at a canister pressure, with the canisterpressure generally being higher than a fully inflated balloon pressureso that no pumps or the like are needed to transfer the liquid from thecanister to the balloons. The liquid may, when at body temperature,vaporize into the inflation gas, with the vaporization typicallyoccurring at a vaporization pressure that is less than the canisterpressure and more than the fully inflated balloon pressure. Note,however, that the balloon pressure may approach or even exceed thecanister pressure, for example, when the valves are closed and thearticulated structure is subjected to sufficient environmental pressureto compress a fully inflated balloon. While the enthalpy of vaporizationmay result in localized cooling along the system, in many embodiments notherapeutic cooling of tissues or other structures may be provided, andmuch or all of the liquid may be vaporized prior to the inflation fluidreaching the balloon(s). Other embodiments may make use of a portion ofthe liquid from the source for cryogenic cooling (typically near adistal end of the articulated structure), but will often provide aseparate cryogenic cooling channel along the articulated body for suchcooling so as to improve articulation response, though such cooling maymake use of a separate cooling fluid supply canister than that of thearticulation system, with that canister typically containing a largerquantity of the same (or a different) cryogen.

Independent of the specific embodiment, one or more of a number ofdifferent features can be provided to enhance functionality. The fluidsupply often maintains the liquid with a pressure of over 40 atm., withthe fluid supply optionally having a heater to keep the canister at arelatively constant temperature and pressure during use of the system. Afirst valve can be disposed between the fluid source and the firstballoon, and a second valve can be disposed between the fluid source andthe second balloon. The first and second valves can be configured toindependently transmit minimum increments of 50 nl or less of theliquid, with the flowing cooling fluid often remaining liquid till ittraverses a throat of the valve. A third valve can be disposed betweenthe first balloon and a surrounding atmosphere, and a fourth valve canbe disposed between the second balloon and the surrounding atmosphere.The third and fourth valves can be configured to independently transmitat least 0.1 scc/s of the gas. Including all four such valves in thesystem may facilitate independent pressure control over two balloons (ortwo subsets of balloons, with each subset being inflated using a commoninflation lumen), with additional inflation and deflation valves foradditional balloons (or subsets of balloons). Optionally, the minimumliquid increment for inflation may be 25 nl (or even 15 nl) or less,while the minimum gas flow for deflation may be 0.5 scc/s (or even 1scc/s) or more. The system may employ multi-way valves that can be usedto control both inflation fluid flowing into the balloon and deflationfluid exhausted from the balloon, with accuracy of control (despite thedifferent inflation and deflation flows) being maintained by differingvalve throats, by differing orifices or other flow restricting devicesadjacent the valve(s), by proportional flow control of sufficient range,and/or by a sufficiently rapid valve response rate. Apressure-controlled plenum can be disposed between the fluid source andthe first and second balloon, or the liquid may otherwise vaporize tothe gas before the valve so that none of the liquid transits a valvesbetween the plenum and the balloons.

In a related method aspect, the invention provides an articulationmethod comprising transmitting liquid from a fluid source and along anelongate flexible body. The liquid vaporizes to an inflation gas. Aplurality of balloons disposed along the flexible body are inflatedusing the inflation gas so that the balloons alter a bend characteristicof the flexible body.

In another aspect, the invention provides an articulatable structurecomprising an elongate flexible body having a proximal end and a distalend with an axis therebetween. A plurality of balloons is disposed alongthe body, the balloons inflatable from a first configuration to a secondconfiguration such that the balloons alter a bend state of the body. Aflexible sheath is disposed around the balloons. The sheath is sealed soas to form a pressure chamber with the balloons disposed therein.

Optionally, the elongate body comprises a catheter body, and the distalend is configured for insertion into a patient. The chamber can flexlaterally with the catheter body, and a pressure sensing lumen mayextend proximally from the chamber toward the proximal end. The balloonscan be supported by and/or mounted on a substrate, and the substrate cancontain a plurality of lumens for inflating the balloons along with thepressure sensing lumen. An exemplary substrate comprises a multi-lumenshaft, the balloons having balloon walls extending around the shaft.

Any of a number of features can be included to enhance the functionalityof the chamber. Optionally, a vacuum source may be in fluidcommunication with the chamber so as to reduce a pressure of thechamber, so that the chamber comprises a vacuum chamber. The elongatebody will preferably remain flexible while the chamber is under avacuum, with the vacuum typically being from a few inches of mercury tohalf an atmosphere or more. A fluid control system having a sensor canbe coupled with the chamber, and a shut-off valve can be disposedbetween an inflation fluid source and the balloons. The shut-off valvecan inhibit inflation fluid flow to the balloons in response to signalsfrom the sensor indicating that the vacuum is degrading, as such signalsmay be associated with a leak of the inflation fluid, a leak of theouter sheath, a leak of an inner sheath to which the outer sheath issealed, a leak of a proximal and/or distal seal of the chamber, or thelike. Hence, the use of the chamber can significantly enhance safety andserve as a fault-detection system that identifies and preventsundesirable or dangerous leakage, thereby facilitating (for example) useof gas as an inflation fluid for catheters or the like.

In a related aspect, the invention provides a method comprisinginflating a plurality of balloons disposed along an elongate flexiblefrom a first configuration to a second configuration such that theballoons alter a bend state of the body. A sheath disposed around theballoons flexes with lateral flexing of the body, the sheath sealed soas to form a pressure chamber with the balloons disposed therein.

In another aspect, the invention provides a structure comprising anelongate flexible skeleton having a proximal end and a distal end withan axis therebetween. The skeleton has a plurality of pairs of interfaceregions distributed along the axis, and offsets can be defined betweenthe pairs of interface regions, with the offsets varying with flexing ofthe skeleton. An array of balloons can be operatively coupled with theoffsets of the skeleton such that inflation of at least some of theballoons alters a lateral bending stiffness of the skeleton.

Advantageously, the controlled stiffness provided by a balloon array canbe varied along a length of a catheter or other flexible structure, canbe varied circumferentially (so as to provide differing stiffness indiffering lateral bending orientations), and/or may be modulated so asto provide any of a plurality of different local or global stiffnesses,and/or to provide a desired stiffness anywhere within a continuousrange. For example, the skeleton may have a first axial segment and asecond axial segment, and the pairs of offsets may be distributedaxially along the first and second axial segments. Selectivelyincreasing or decreasing inflation of a first subset of the balloonsdisposed along the first segment may be used to inhibit or facilitatechanges to the offsets along that first segment so as to selectivelyincrease or decrease a lateral bending stiffness of the first segment(respectively). The second segment stiffness (and/or a stiffness of athird, fourth, or other segments) may be independently altered. Asanother example, the skeleton may have a first lateral bendingorientation and a second lateral bending orientation, and the pairs ofoffsets may be distributed circumferentially along the first and secondlateral bending orientations. Selectively increasing or decreasinginflation pressure of a first subset of the balloons disposed along thefirst lateral bending orientation can inhibit or facilitate changes tothe offsets along the first lateral bending orientation so as toselectively increase or decrease a lateral bending stiffness in thefirst lateral bending orientation, respectively, while alteringinflation of second, third, or optionally fourth subsets of offsets maysimilarly alter lateral bending stiffness along second, third, or fourthlateral orientations (with opposed orientations often being coupled).

A number of different approaches may be employed to provide control overstiffness. The skeleton and array may be configured so that decreasingan inflation pressure of a first subset of balloons increases a lateralbending stiffness of the skeleton. For example, when the skeleton is inthe form of a helical coil that is biased to a straight configurationhaving direct loop/loop engagement, the first subset of balloons mayhave balloon walls positioned between apposed interface regions ofadjacent loops, so that inflation of the balloons may locally weaken acolumn strength of the skeleton. More specifically, the loops can bebiased to compress and deflate the balloons, so that axial forces aretransmitted between loops by solid materials of the loops and balloonwalls when the balloons are fully deflated, thereby providing a firstlateral stiffness. In contrast, axial forces may be transmitted by fluidpressure within the balloons when the balloons are partially inflated soas to provide a second lateral stiffness that is lower than the firstlateral stiffness.

Alternatively, increasing an inflation pressure of a first subset ofballoons may increase a lateral bending stiffness of the skeleton. Forexample, the interface regions of the pairs may be oriented radially,and the first subset of balloons may span the pairs of interfacesurfaces and may radially engage the interface surfaces when the firstsubset of balloons are inflated. The fluid pressure of the inflatedballoons can thereby urge the inflated balloons against the interfaceregions so as to inhibit changes in the associated offsets. As anotherexample, the first subset of balloons may comprise a pair of opposedballoons disposed in a channel of the skeleton with a flange of theskeleton between the opposed balloons. The offsets may compriseseparations between apposed surfaces of the flange and the channel, andincreasing inflation pressure of the apposed balloons may increase astiffness of the position of the flange within the channel, and hencethe overall lateral bending stiffness of the skeleton. Advantageously,the flange and the channel may comprise helical structures engaged by aplurality of opposed pairs of balloons, and the offsets may extendprimarily axially, and may angle circumferentially with the pitch of thehelical structures.

In a related method aspect, the invention provides a method comprisinginflation of at least some balloons included in an array of balloons.The array is supported by an elongate flexible skeleton, and theskeleton has a plurality of pairs of interface regions distributed alongan axis of the skeleton, the pairs of interface regions defining offsetsthat vary with flexing of the skeleton. The inflated balloons areoperatively coupled with the offsets of the skeleton such that theinflation of the balloons alters a lateral bending stiffness of theskeleton.

In another aspect, the invention provides a flexible catheter comprisinga helical skeleton structure having a proximal end, a distal end, and anaxis therebetween. The distal end is configured for insertion into apatient. An array of balloons is supported by the helical skeleton, thearray comprising balloons distributed axially and circumferentiallyabout the skeleton. A fluid supply system is in fluid communication withthe balloons, and is configured to selectively inflate any of aplurality of subsets of the balloons so as to selectively alter a shapeand/or stiffness of the helical skeleton.

A number of features may be provided to enhance functionality of thecatheters provided herein, many of which are identified in the precedingand following paragraphs. As another example, an unarticulated flexibleproximal body portion of the catheter may be disposed between theproximal end and the balloon array. Fluid channels can span the proximalbody portion, but may not provide control over a shape (and optionally,may not even allow control over stiffness) of that portion. This canhelp keep the complexity and size of the system down, with anyarticulation functionality being concentrated along a distal portion andthe proximal portion being configured to flex to follow a body lumen orthe like.

In a related aspect, the invention provides a method comprisingselectively inflating a first subset of balloons, the balloons includedin an array of balloons supported by a helical skeleton. The array isdistributed axially and circumferentially about the skeleton. Theinflation of the first subset inducing a first change in the shapeand/or stiffness of the helical skeleton. A second subset of theballoons is selectively inflated, the inflation of the second subsetinducing a second change in the shape and/or stiffness of the helicalskeleton. The second change in shape and/or stiffness is offset axiallyand/or circumferentially from the first change.

In another aspect, the invention provides a fluid supply system for usewith an articulatable catheter. The catheter has a skeleton structureand an array of balloons supported by the skeleton, the fluid supplysystem comprises a fluid source configured for providing an inflationfluid at a source pressure. A channel system is in fluid communicationwith the fluid source, the channel system having a plurality of channelsfor transmitting the fluid toward the balloons of the array. A pluralityof valves is disposed along the channels, and a processor is coupledwith the valves. The processor is configured to actuate the valves so asto selectively inflate subsets of the balloons to control a shape and/orstiffness of the catheter.

Having processor-controlled valves is an optional feature of the systemsand devices described herein, and any of a range of refinements may beincluded to further enhance capabilities of the system. Rather thanhaving to resort to heavy and complex motors and pumps, by using asimple fluid source (such as a pre-pressurized canister or the like) andprocessor controlled valves (optionally including at least 8, 16, 32, oreven 64 valves), the system can control shape and/or stiffness of anelongate flexible system with large number of degrees of freedom. Wherea processor is provided, a plurality of pressure sensors may couple someof the channels with the processor, the processor configured to actuatethe valves so as to control pressure within the subsets of balloons.With or without processor controlled valves, another optional feature isthat the articulation devices may have balloon arrays with at least 9,18, 36, 72, or even 108 balloons. Where the articulated catheter has anouter cross-sectional diameter, the balloon array may have an axialdensity of at least 3, 4, 6, 8, or even 9 balloons per diameter of axiallength to provide, for example, a desirable bend capability.

In another aspect, the invention provides an articulatable devicecomprising a skeleton having a proximal end and a distal end with anaxis extending therebetween. The skeleton has an axial lumen and aplurality of pairs of interface regions with offsets therebetween, theoffsets varying with articulation of the skeleton. A multi-lumen shaftbody disposed in the lumen of the frame, the shaft having a plurality oflumens extending along the axis. An array of balloons is in fluidcommunication with the lumens of the multi-lumen shaft body. Theballoons of the array are eccentric of the multi-lumen shaft anddisposed in the offsets of the skeleton.

The structures described herein will often include simple balloonarrays, with inflation of the balloons interacting with elongateskeletal support structures so as to locally alter articulation of theskeleton. The balloons can be mounted to a substrate of the array, withthe substrate having channels that can direct inflation fluid to asubset of the balloons. The skeleton may comprise a simple helical coil,and the array can be used to locally deflect or elongate an axis of thecoil under control of a processor. Inflation fluid may be directed tothe balloons from an inflation fluid reservoir of an inflation system,with the inflation system preferably including valves controlled by theprocessor. Such elongate flexible articulation structures can beemployed in minimally invasive medical catheter systems, and also forindustrial robotics, for supporting imaging systems, for entertainmentand consumer products, and the like. As the articulation array structuremay be formed using simple planar 3-D printing, extrusion, and/ormicromachining techniques, the costs for producing structures havinglarge numbers of kinematic degrees of freedom may be much, much lowerthan those associated with known powered articulation techniques.

The devices, systems, and methods described herein can selectively,locally, and/or reversibly alter the bend characteristics of an elongatebody. Bending of an elongate body is addressed in detail herein, andsome of the technologies described herein are also suitable for alteringthe stiffness along an elongate catheter body, with the stiffness oftenbeing altered by inflation of one or more balloons. A number ofdifferent stiffening approaches may be employed. Optionally, inflationof a balloon can induce engagement between the balloon and the loops ofa helical, cut-tube, braided, or other elongate flexible skeleton, sothat the balloon may act as a brake or latch to inhibit flexing. Theballoon will often be eccentrically mounted relative to the skeleton,and may be included in a balloon array. Selective inflation of a subsetof the balloon array can selectively and locally increase axialstiffness of the overall body. In other embodiments, modulating aballoon inflation pressure can allow the balloon to variably counteracta compressive force of a helical coil or other biasing structure,effectively modulating the stiffness of an assembly locally adjacent theballoon. In still other embodiments, independently modulating pressureof two opposed balloons can be used to both impose a bend or elongationand to modulate a stiffness in at least one orientation. Hence,stiffening and bending or elongation balloons can be combined, usingeither separate balloon arrays or a multifunctional array havingdiffering types of balloons.

In another aspect, the invention provides an articulatable bodycomprising a multi-lumen helical shaft having a proximal end, a distalend, and an axis therebetween. The shaft defines an axial series ofloops and having a plurality of lumens. A plurality of balloons isdistributed along the loops, each balloon having a balloon wallextending around the shaft. A plurality of ports opens into the shaft,each port providing fluid communication between an associated balloonand an associated lumen.

The balloons can be configured so that inflation of the balloons will,in use, alter a bending state of the articulatable body. Thearticulatable body may include six or more, nine or more, or even 12 ormore balloons, optionally having multiple segments with 12 or moreballoons each, and typically comprises a catheter but may alternativelycomprise an industrial continuum robotic structure, a consumer orentertainment device, or the like. Optionally, a first subset of theballoons is distributed along a first loop and a second subset of theballoons is distributed along a second loop; a plurality of additionalsubsets may be distributed along other loops. In those or otherembodiments, a third subset of the balloons can be offset from the axisand aligned along a first lateral bending orientation, and a fourthsubset of the balloons can be offset from the axis and aligned along asecond lateral bending orientation offset from the axis and from thefirst lateral orientation. The ports associated with the third subset ofballoons may be in fluid communication with a first lumen of the shaft,and the ports associated with the fourth subset of balloons may be influid communication with a second lumen of the shaft. The third andfourth subsets will often include balloons of the first, second, andother subsets, and yet another subset of the balloons can be offset fromthe axis and aligned along a third lateral orientation offset from thefirst and second lateral orientations.

In most embodiments, the balloons define an M×N array, with M lateralsubsets of the balloons being distributed circumferentially about theaxis, each of the M lateral subsets including N balloons aligned alongan associated lateral bending orientation. For example, M may be threeor four, so that there are three or four lateral subsets of balloonsdistributed about the axis of the articulatable body (the centers of thesubsets optionally being separated by 120 or 90 degrees). Note thatthere may be some coupling between an axial elongation state of anarticulated segment and the lateral bending orientations, for example,with the helical coil unwinding slightly when the segment increases inlength, so that a line connecting the centerlines of the N balloons maycurve or spiral slightly along the axis in at least some configurationsof the segment (rather than the N balloons always being exactly inalignment parallel to the axis). The ports associated with the balloonsof each of the M lateral subsets may provide fluid communication betweenN balloons and an associated lumen, so that each of the lateralorientations is associated with (often being inflated and/or deflatedvia) a particular lumen of the shaft. The array will often comprise afirst array extending along a first segment of the articulatable body.The first segment can be configured to be driven in two, three, or moredegrees of freedom by fluid transmitted along the lumens associated withthe M lateral subsets of the first array. A second segment of thearticulatable body can also be provided, typically axially offset fromthe first segment. The second segment can have a second array and can beconfigured to be driven in a plurality of degrees of freedom by fluidtransmitted along lumens of the shaft associated with the second array,which will often be separate from those of the first array.Articulatable bodies may have from 1 to 5 independently articulatablesegments or more, with each segment preferably providing from one tothree degrees of freedom, each segment often being configured to haveconsistent bend characteristics and/or elongation between its proximalend and distal end, but the different segments being driven to differentbend and/or elongation states.

In many embodiments, the balloon walls comprise a non-compliant balloonwall material, although semi-compliant wall materials may be used, withthe balloons often being small enough and having sufficient thickness toallow pressures beyond those used in larger balloons, often includingpressures above 20 atm., 30 atm, or even 40 atm. Preferably, at leastsome of the balloons comprise a continuous balloon wall tube sealinglyaffixed around the shaft at a plurality of seals. The seals can beseparated along the shaft axis so that the tube defines the balloonwalls of the plurality of balloons. The balloon wall tube can have aplurality of balloon cross-section regions interleaved with a pluralityof seal cross-section regions, the balloon cross-section regions beinglarger than the seal cross-section regions to facilitate fluid expansionof the balloons away from the shaft. Optionally, a reinforcement bandcan be disposed over the balloon adjacent the seal so as to inhibitseparation of the balloon from the shaft associated with inflation ofthe balloon. Suitable reinforcement bands may comprise a metal structuresimilar to a marker band that is swaged over the balloon tube and shaftalong the seal, a fiber that is wound on, or the like. Typically, anelongate structural skeleton will support the multi-lumen shaft, theskeleton having pairs of interface regions separated by axial offsets,the offsets changing with flexing of the skeleton, wherein the balloonsare disposed between the regions of the pairs.

In another aspect, the invention provides an articulatable bodycomprising an elongate flexible skeleton having a proximal end and adistal end and defining an axis therebetween. The skeleton has pairs ofinterface regions separated by offsets; the offsets change with flexingof the skeleton. A substrate can be mounted to the frame, and aplurality of balloons can be supported by the substrate. The balloonscan be distributed axially and circumferentially about the skeleton, andcan be disposed between the regions of the pairs. A channel system maybe disposed in the substrate so as to provide fluid communicationbetween the proximal end of the frame and the balloons.

Optionally, the substrates of the system provided herein may have firstand second opposed major surfaces and a plurality of layers extendingalong the major surfaces. The channel system can be sealed by bondinglayers of the substrate together. The substrate can be curved in acylindrical shape, for example, by rolling a substrate/balloon assemblyafter it has been fabricated in a planar configuration. A plurality ofvalves can be disposed along the channels so as to provide selectivefluid communication between the proximal end and the balloons.Optionally, the balloons can have balloon walls that are integral with afirst layer of the substrate, such as by blowing at least a portion of ashape of the balloon from the layer material.

Alternatively, the substrate may comprise a helical multi-lumen shaft.The balloon array optionally comprises an M×N array of balloonssupported by the substrate, with M being three or four such that 3 orfour subsets of balloons are distributed circumferentially about theaxis. Each of the M subsets can aligned along an associated lateralorientation offset from the axis. N may comprise 2, such that each ofthe M subsets includes two or more axially separated balloons.

In another aspect, the invention provides a method for making anarticulatable structure. The method comprises providing a multi-lumenshaft having a proximal end and a distal end with a shaft axistherebetween. A plurality of lumens can extend along the shaft axis.Ports can be formed into the lumens, the ports being disposed within aplurality of balloon regions. The balloon regions can be separated alongthe shaft axis. A balloon wall tube can be provided, with the balloontube having a proximal end and a distal end with a lumen extendingtherebetween. The shaft can be sealed within the lumen of the balloontube at a plurality of seals between the balloon regions so as to form aplurality of balloons. The shaft axis may comprise a helix having aplurality of loops and the balloons can be disposed on a plurality ofseparate loops.

As a general approach, the shaft axis can be straight during the sealingof the shaft within the lumen of the balloon tube. Hence, the shaft maybe bent with the balloon tube to form a helical shaft. Alternatively,the shaft may be slid into the lumen of the balloon tube after bendingthe shaft in some embodiments.

In another aspect, the invention provides a method for articulating anarticulatable body. The method comprises transmitting fluid along aplurality of lumens of a helical multi-lumen shaft, with the shaftdefining a series of loops. A plurality of balloons is inflated with thetransmitted fluid. The balloons are distributed along the loops, eachballoon having a balloon wall extending around the shaft. The inflatingof the balloons is performed by directing the fluid radially from thelumens through a plurality of ports so that each port provides fluidcommunication between an associated lumen and an associated balloon.

In yet another aspect, the invention provides a method for articulatingan articulatable body. The method comprises transmitting fluid along achannel system disposed in a substrate. The substrate is mounted to anelongate flexible skeleton and supports a plurality of balloons. Theelongate flexible skeleton has pairs of interface regions separated byaxial offsets, and the balloons are disposed between the regions of thepairs. The fluid is directed to the balloons with the channel system sothat a subset of the balloons expands. The balloons are distributedaxially and circumferentially about the skeleton and are disposed in theoffsets. The expanding of the subset of balloons changes a bend state ofthe skeleton.

The loops can have proximal interface regions and distal interfaceregions. The balloons may comprise expandable bodies, and the balloonsthat are between loops may be disposed between a distal interface of thefirst associated loop and a proximal interface of the second associatedloop, the proximal and distal interfaces defining pairs of interfacesand having offsets therebetween. The balloons may optionally be mountedover a third loop of the coil between the first and second loops, or onan additional helical structure having loops between the loops of thehelical coil. The helical coil may be included in a skeleton of thearticulation system.

The substrate may comprise a flexible multi-lumen shaft or tubular body,optionally including an extruded polymer multi-lumen tube with thechannels being defined by the extruded lumens together withmicromachined radial ports; the multi-lumen tubular body ideally bendingto follow a helical curve. The skeleton may be integrated into such amulti-lumen helical body, disposed within such a multi-lumen helicalbody, or interleaved with such a multi-lumen helical body. The actuationarray may also include a plurality of fluid-expandable bodiesdistributed across and/or along the substrate. The expandable bodies canbe coupled with associated pairs of the interfaces, and the channels canprovide fluid communication between the expandable bodies and the fluidsupply system so as to facilitate selective inflation of a subset of theexpandable bodies. Advantageously, the expandable bodies can beoperatively coupled to the offsets so that the selective inflationalters articulation of the skeleton adjacent the subset.

The skeleton may comprise a tubular series of loops, such as when theskeleton is formed from a helical coil, a braid, a hypotube or othermedical-grade tubular material having an axial series of lateralincisions or openings so as to provide more lateral flexibility than acontinuous tube would have, or the like. Each pair of interfaces maycomprise, for example, a first associated surface region of a firstassociated loop and a second associated surface region of a secondassociated loop adjacent the first loop, so that inflation of theexpandable bodies can alter flexing of the skeleton between the loops.Note that expandable bodies that are coupled to a pair of interfaces mayoptionally be coupled to only the pair of interfaces (so that inflationof that structure does not largely alter flexing of the skeleton betweenother loops), but that in other embodiments the expandable body may becoupled with not only the pair of loops but with one or more additionalloops so that flexing of the skeleton may be altered over an axialportion extending beyond the pair. As an example, an elongate balloonmay extend axially along an inner or outer surface of several loops, sothat when the balloon is inflated bending of the coil axis along thoseloops is inhibited.

Where at least some of the expandable bodies or balloons are coupledwith pairs of interfaces, the first interfaces of the pairs mayoptionally be distally oriented and the second interfaces of the pairsmay be proximally oriented, with the precise orientation of theinterfaces optionally angling somewhat per a pitch of a helical framestructure. The relevant expandable bodies can be disposed axiallybetween the first and second interfaces. Expansion of each of theseexpandable bodies may urge the associated loops of such pairs apart,often so that the skeleton adjacent the associated first and secondloops bends laterally away from the expanded balloon. A lateralorientation of the bend(s) relative to the skeletal axis may beassociated with the location of the expandable bodies relative to thataxis. A quantity or angle, an axial location, and/or a radius of thearticulation or bend imposed by any such inflation may be associatedwith characteristics of the expandable body or bodies (and theassociated changes in offset they impose on the skeleton due toinflation), with characteristics of the skeleton, with location(s) ofthe expandable body or bodies that are expanded, and/or with a numberand density of the bodies expanded. More generally, bend characteristicsmay be selected by appropriate selection of the subset of expandablebodies, as well as by the characteristics of the structural componentsof the system.

At least some expandable bodies or balloons of the array (or of anotherseparate articulation array) may be mounted to the skeleton or otherwiseconfigured such that they do not force apart adjacent loops to imposebends on the axis of the skeleton. In fact, some embodiments may have nofluid-expandable structure that, upon expansion or deflation but withoutan external environmental force, induces bending of the skeleton axis atall. As an optional feature, one or more of the expandable bodies orballoons of the actuation arrays described herein may optionally be usedto locally and reversibly alter strength or stiffness of the skeleton,optionally weakening the skeleton against bending in a lateralorientation and/or at a desired axial location. In one particularexample, where the skeleton comprises a resilient helical coil in whicha pair of adjacent coils are resiliently urged against each other by thematerial of the coil, a balloon (or set of balloons) disposed axiallybetween one pair of loops of the coil (or a set of loops) may beinflated to a pressure which is insufficient to overcome the compressiveforce of the coil, but which will facilitate bending of the coil underenvironmental forces at the inflated pair (or pairs). More generally,inflation of a subset of balloons may locally weaken the coil so as topromote bending under environmental forces at a first location, andchanging the subset may shift the weak location (axially and/orcircumferentially) so that the same environmental stress causes bendingat a different location. In other embodiments, the interfaces may, forexample, include a first pair, and a first interface of the first pairmay be radially oriented. Similarly, a second interface of the firstpair may be radially oriented, and a first expandable body may beradially adjacent to and extend axially between the first and secondinterfaces of the first pair so that expansion of the first expandablebody axially couples the first expandable body with the first and secondinterfaces of the first pair. This axial coupling may result in thefirst expandable body supporting the relative positions of theinterfaces of the pair, inhibiting changes to the offset between theinterfaces of the first pair and helping to limit or prevent changes inbend characteristics of the axis of the skeleton adjacent the first pairwhen the expandable body is expanded. Advantageously, if such anexpandable body is expanded when the axis is locally in a straightconfiguration, the expandable body may prevent it from bending; if suchan expandable body is expanded when the axis is locally in a bentconfiguration, it may prevent the axis from straightening.

In any of the articulation systems described above, the pairs mayinclude a first pair of the interfaces offset laterally from the axisalong a first lateral axis. An associated first expandable body may bedisposed between the interfaces of the first pair. In such embodiments,a second expandable body may be disposed between a second pair of theinterfaces that is offset laterally from the axis along a second lateralaxis transverse to the first lateral axis. Hence, inflation of thesecond expandable body may bend the axis of the skeleton away from thesecond lateral axis and inflation of the first lateral body may bend theaxis of the skeleton away from the first lateral axis. In otherembodiments, a second pair of the interfaces may be offset laterallyfrom the axis and may be opposed to the first lateral axis and to thefirst pair so that the axis extends between the first pair and thesecond pair, such that inflation of a second expandable body disposedbetween the second pair together with the first expandable body urgesthe skeleton to elongate axially. In still other embodiments, a secondexpandable body may be disposed between a second pair of the interfaces,with the second pair axially offset from the first pair and sufficientlyaligned along the first lateral axis with the first pair so thatinflation of the first expandable body urges the skeleton to bendlaterally away from the first lateral axis, and inflation of the secondexpandable body together with the first expandable body urges theskeleton to bend laterally further away from the first lateral axis. Ofcourse, many embodiments will include multiple such combinations ofthese structures and capabilities, with a plurality of pairs being alonglaterally offset, a plurality being opposed relative to the axis, and/ora plurality being axially aligned so that by inflating appropriatesubsets of the expandable bodies (as disposed between associatedpluralities of pairs of interface surfaces or structures), the axis canbe bent laterally in a single orientation by different incrementalamounts, the skeleton can be axially lengthened by different incrementalamounts, and/or the axis can be bent laterally in a plurality ofdifferent lateral orientations by differing incremental amounts, allsequentially or simultaneously. Combinations of any two or more of thesedesired structures and capabilities can be provided with the relativelysimple structures described herein.

Optionally, the expandable bodies may comprise non-compliant balloonwalls, and each expandable body can have an expanded configurationdefined by expansion with a pressure within a full expansion pressurerange, and an unexpanded configuration. The offsets of the skeleton canhave associated open and closed states, respectively. The skeleton(and/or structures mounted thereto) will optionally be sufficientlybiased to urge the axial offsets toward a closed state when the balloonsare in the unexpanded configuration and no environmental loads areimposed.

The skeletons and arrays will often be included in a catheter configuredfor insertion into a body of a patient. The articulation systems formedical or non-medical uses may also include an input configured forreceiving a catheter articulation command from a user, and a processorcoupling the input to the fluid supply source. The processor may beconfigured to selectively direct the fluid to a subset of the expandablebodies in response to the command. For example, when the input isconfigured so that the command comprises a desired direction ofarticulation, and when the fluid supply comprises a plurality of valvescoupled to the plurality of channels, the processor may identify andactuate a subset of the valves in response to the direction. A number ofadditional and/or alternative relationships between the input commandsand valves may also be incorporated into the processor. As alternativeexamples (that may or may not be combined with the preceding exampleand/or with each other) when the input is configured so that the commandcomprises a desired location of articulation, the processor may identifyand actuate a subset of valves in response to the location; when theinput is configured so that the command comprises a radius ofarticulation, the processor may identify and actuate a subset of valvesin response to the radius; when the input is configured so that thecommand comprises a desired axial elongation quantity, the processor mayidentify and actuate a subset of valves in response to the elongationquantity; etc.

The systems may operate in an open-loop manner, so that the actualarticulation actuation is not sensed by data processing components ofthe system and feed back to any processor. Other systems may includecircuitry to generate feedback signals indicative of the state of someor all of the balloons or offsets optionally by printing or otherwiseincluding appropriate electrical components on or in the balloon walls.Some embodiments may sense an orientation (and/or relative position) ofa proximal or “base” portion of the skeleton adjacent the array-drivendistal portion so as to align desired and commanded orientations,regardless of any movement control feedback, with suitable positionand/or orientation sensors optionally being selected from among knowncomponents that rely on imaging technologies (such as optical,fluoroscopic, magnetic resonance, ultrasound, computed tomography,positron emission tomography, or the like) and use known imageprocessing techniques, and/or being selected from known minimallyinvasive tool tracking technologies (such as electrical, ultrasound, orother inserted device and active fiducial locating systems), and/orbeing selected from known catheter bend monitoring techniques (such asoptical fiber systems or the like). Processors of some embodiments mayemploy any of these or other sensors for feedback on the actuallocation, orientation, movement and/or pose and for determining furthervalve actuation signals.

Optionally, a plurality of the valves may be coupled to the proximal endof the skeleton. Instead (or in addition), a plurality of the valves maybe disposed along the array. For example, the substrate of the array maycomprise first and second substrate layers with a substrate layerinterface therebetween, and the channels may comprise channel wallsextending into the first layer from the substrate interface.

The expandable bodies of any of the arrays described herein may bedistributed axially and circumferentially along the substrate, so thatthe array may define (for example) an at least two dimensional array.Actuation fluid containment sheathing may encase the skeleton andballoons, with the sheathing optionally being integrated with thesubstrate. This may allow used inflation fluid to flow proximally fromthe balloons outside the channels of the substrate and therebyfacilitate balloon deflation without releasing the used inflation fluidinside a body or the like.

In another aspect, the invention provides an articulation cathetersystem comprising a catheter body having a structural skeleton with aproximal end and a distal end and defining an axis therebetween. Theskeleton may have a plurality of pairs of interfaces, each pairincluding a first interface and a second interface with an offsettherebetween. The offsets may vary with articulation of the skeleton soas to define an articulation state. An array of actuation balloons mayalso be provided, with each balloon operatively associated with anoffset between a first associated interface and a second associatedinterface, and also having a first profile configuration. An input forreceiving an articulation command can also be included, along with asensor for determining sensor data indicating a position of the skeletonadjacent the first pair, an orientation of the skeleton adjacent thefirst pair, and/or an articulation state of the skeleton adjacent thefirst pair. A fluid supply system may be in fluid communication with thearray of balloons. The fluid system can comprise a processor coupled tothe input and the sensor. The processor may be configured to directactuation fluid toward a subset of the balloons so as to urge eachballoon of the subset to expand from the first profile configuration toa second profile configuration so as to alter articulation of theoffset(s) adjacent the subset. The processor may be configured todetermine the subset in response to both the command and the sensordata.

In a method aspect, the invention provides a method for articulating anarticulation system. The method comprises directing fluid from a fluidsupply toward one or more balloons of an array. Each balloon is disposedbetween a first associated loop and a second associated loop of anelongate helical coil, the second associated loop being adjacent thefirst associated loop. The helical coil may have a proximal end and adistal end and may define an axis therebetween. The fluid can bedirected so as to expand the balloon(s) from a first profileconfiguration to a second profile configuration such that the associatedloops are urged apart by the expanded balloons, and such that an axialbending characteristic of the coil is altered. After the expansion ofthe balloon(s), biasing of the helical coil may urge the balloon(s) backtoward the first profile configuration.

In another method aspect, the invention provides a method forarticulating an articulation system. The method comprises directingfluid from a fluid supply system into at least one channel of a flexiblesubstrate, the substrate included within an actuation array and havingopposed major surfaces. The actuation array may also include a pluralityof fluid-expandable bodies distributed across the substrate. Thechannels may direct the fluid into a subset of the expandable bodies sothat the fluid inflates the subset. The subset of expandable bodies maybe urged against a plurality of interface surfaces of a structuralskeleton by the expansion. The structural skeleton may have a proximalend and a distal end with an axis therebetween, and the urging may beperformed so as to alter bend characteristics of the axis adjacent thesubset.

In another aspect, the invention provides a method for fabricating anarticulation structure, the method comprising forming a plurality ofchannels in a flexible substrate, the substrate having first and secondopposed major surfaces and the channels being disposed between the majorsurfaces. A plurality of expandable bodies are formed in or affixed tothe substrate so as to define an array, the channels in fluidcommunication with the expandable bodies so that fluid from the channelscan expand the fluid-expandable bodies.

Prior to use, the array will often be coupled with a skeleton structureso that expansion of the expandable bodies alters an axis of theskeleton. Typically, the flexible substrate will be flexed from aninitial shape during mounting of the array to the skeleton, and may alsobe further flexed during articulation of the skeleton by the array.

In yet another aspect, the invention provides a controllably flexiblecatheter (or other elongate body). The catheter (or other body)comprises an elongate structural skeleton having a proximal end and adistal end and defining an axis therebetween. The skeleton has an axialseries of circumferential loops including a first loop and a secondloop. A first balloon extends along the first and second loops of theskeleton, the first balloon expandable from a deflated configuration toan inflated configuration. The first loop can move axially relative tothe second loop during bending of the axis relatively freely when thefirst balloon is in the deflated configuration. However, the firstballoon radially engages the first and second loops in the inflatedconfiguration so that the balloon inhibits bending of the axis when thefirst balloon is in the inflated configuration.

Optionally, the skeleton may include a helical coil, which may havespaces between the loops when in a relaxed state or the coil may insteadbe biased so that adjacent loops of the coil axially engage each otherwhen the coil is in a relaxed state, which can help to transmit axiallycompressive loads between the loops. Alternative skeletons may includehypotube or other tubing having a plurality of lateral slots so as todefine the loops there between, and/or a braided tubular structurehaving a plurality of braid elements defining the loops.

Typically, the first balloon is eccentric of the skeleton and isdisposed radially between the skeleton and a radial support structure.The radial support can have opposed inner and outer surfaces and can beconfigured to limit radial displacement of the first balloon relative tothe skeleton during expansion, so that expansion of the first balloonfrom the deflated configuration to the inflated configuration inducesthe desired bend-inhibiting radial engagement between the first balloonand the first and second loops of the skeleton. Suitable radial supportsmay comprise a helical coil or even a circumferential band of material,often being a polymer material disposed radially outward of the skeletonso that expansion of the first balloon imposes a circumferential tensileload in the band. The radial support may optionally be integrated into asubstrate of a balloon array, with the first balloon being included inthe array structure.

Optionally, the first balloon is included in an array of balloonsdistributed along the skeleton, circumferentially, axially, or both.Each of the balloons is expandable from a deflated configuration to aninflated configuration, and some or all of the balloons have a pluralityof associated loops of the skeleton including a first associated loopand a second associated loop, the first associated loop movable axiallyrelative to the second associated loop during bending of the axisadjacent the balloon when the balloon is in the deflated configuration.These balloons each radially engage the first and second associatedloops in the inflated configuration so as to inhibit relative axialmovement and bending of the axis adjacent those balloon when theballoons are in the inflated configuration. A fluid supply system willoften be in fluid communication with the balloons during use so as toselectively inflate a desired subset of the balloons such that bendingof the axis adjacent the subset is inhibited. In some exemplaryembodiments, these balloons are circumferentially distributed about theskeleton, and inflation of a first subset of the balloons distributedabout a first axial segment of the skeleton inhibits bending of theskeleton in orthogonal bend orientations across the axis along the firstsegment. A second subset of the balloons extend along a second axialsegment of the skeleton can also be provided, the second segment axiallyadjacent to or overlapping with the first segment and at least partiallyextending axially beyond the first segment so that inflation of thefirst and second subsets inhibits axial bending of the skeleton in theorthogonal bend orientations contiguously along the first and secondaxial segments of the skeleton. The balloon arrays for inhibitingbending can be combined with balloon arrays for selective articulation(either by providing both types of balloon arrays or by including bothtypes of balloons in an integrated array), and the arrays may sharesubstrate, channel, and/or fluid control components and techniques.

In yet another aspect, the invention provides a catheter comprising anelongate skeleton having a proximal end and a distal end with an axistherebetween. The skeleton includes an axial series of loops, andoffsets between the loops vary with axial flexing of the skeleton. Anarray of balloons is distributed along the skeleton. Each balloon: 1)extends along an associated plurality of the loops; 2) has a firstconfiguration and a second configuration; and 3) radially engages theassociated loops so as to inhibit changes in the offsets when theballoon is in the second configuration, and thereby inhibits axialbending of the skeleton between the associated loops.

In yet another aspect, the invention provides a catheter comprising anelongate skeleton having a proximal end and a distal end with an axistherebetween. A substrate is supported by the skeleton, the substratehaving a plurality of channels. A plurality of balloons are distributedalong the substrate and in fluid communication with the channels. Afluid supply system can be coupled to the proximal end of the skeleton.The fluid supply system directs inflation fluid in the channels so as toexpand one or more of the balloons from an un-inflated configuration toan inflated configuration such that changes to a bend state of the axisalong the inflated balloons are inhibited. The fluid supply system canoptionally include a plurality of valves configured to provide fluidcommunication between a pressurized fluid source and a selectable subsetof the balloons so that axial bending of one or more selectable axialsegments of the skeleton is reversibly inhibited by inflation of thesubset.

In another method aspect, the invention provides a method for using anelongate body, the method comprising moving a flexible shaft. The shafthas an elongate structural skeleton with a proximal end and a distal endand defines an axis therebetween. The skeleton comprises an axial seriesof circumferential loops including a first loop and a second loop. Theshaft is moved with a first balloon of the shaft in a deflatedconfiguration and so that the shaft flexes axially adjacent the firstand second loops and induces associated relative axial movement betweenthe first and second loops. The first balloon is inflated, the firstballoon extending along the first and second loops of the skeleton sothat the first balloon expands from the deflated configuration to aninflated configuration and the first balloon radially engages the firstand second loops. The flexible shaft is moved with the expanded firstballoon so that the balloon inhibits relative axial movement between thefirst and second loops and bending of the axis between the first andsecond loops.

In another aspect, the invention provides an articulation system fordiagnosing or treating a tissue of a patient body. The system comprisesa plurality of balloons, each balloon inflatable from a firstconfiguration to a second configuration. An elongate structural skeletonhaving a proximal end and a distal end defines an axis therebetween. Thedistal end may be configured for insertion into a patient body. Theskeleton may have a plurality of pairs of balloon interface regions,each pair including a proximally oriented region and a distally orientedregion and having an associated balloon disposed therebetween, withthese balloons being among the plurality of balloons. A fluid channelsystem may include at least one fluid supply channel adjacent theproximal end, as well as a balloon inflation channel in fluidcommunication with each of the balloons. These can be used to inflatethe balloons from the first configuration to the second configurationsuch that the inflated balloons urge the associated pairs of interfaceregions apart.

As an optional feature, the skeleton comprises a plurality ofcircumferential loops of a helical coil, the coil including a helicalaxis winding around the axis of the skeleton, and the balloons includeat least one balloon wall disposed around the helical axis along atleast a portion of an associated loop of the coil. The associated pairof regions may be disposed on adjacent loops of the coil, so thatinflation of the balloon may push both adjacent loops away from the loopon which the balloon is mounted. Advantageously, a plurality of balloonsmay be formed from a continuous tube of material over a helical core byintermittently varying the size of the material outward (such as byblowing the material using balloon forming techniques) or inward (suchas by intermittently heat shrinking the material) or both. The core mayinclude one or more balloon inflation lumens, and by appropriatepositioning of the balloons along the helical axis, appropriate sizing,shaping, and spacing of the balloons, and by proving ports through awall of the core into a lumen associated with each balloon, the balloonarray may be fabricated with limited cost and tooling.

The fluid channel system will often comprise one or more helical lumenextending along one or more helical axis of one or more helicalstructures. For example, a first plurality of the balloons can be offsetfrom the axis along a first lateral orientation and in fluidcommunication with the helical lumen, the helical coil comprises a firsthelical coil. A second helical coil may be offset axially from andcoaxial with the first helical coil, the second helical coil havingsecond loops interspersed with the loops of the helical coil along theaxis of the catheter or other elongate body. The second helical coil mayhave a second helical lumen in fluid communication with a secondplurality of the balloons offset from the axis along a second lateralorientation so that transmission of fluid along the first and secondhelical lumens deflects the skeleton along the first and second lateralorientations, respectively.

In some embodiments, the fluid channel system comprises a second helicallumen extending along the helical axis. A first plurality of theballoons may be offset from the axis along a first lateral orientationand in fluid communication with the first helical lumen, and a secondplurality of the balloons may be offset from the axis along a secondlateral orientation and in fluid communication with the second helicallumen. This can allow transmission of fluid along the first and secondhelical lumens of the same helical coil to deflect the axis along thefirst and second lateral orientations, respectively.

The invention also provides an optional manifold architecture thatfacilitates separate computer-controlled fluid-actuated articulation ofa plurality of actuators disposed along the flexible body. The manifoldoften includes fluid supply channels that are distributed across severalregions of a manifold body, the manifold body optionally comprisingmodular plates with plate-mounted valves to facilitate fluidcommunication through a plurality of fluid transmission channelsincluded in one or more multi-lumen shafts of the articulated flexiblebody. The actuators preferably comprise balloons within a balloon array,and will often be mounted on one, two, or more extruded multi-lumenshafts. Valve/plate modules can be assembled in an array or stack, and aproximal interface of the shaft(s) may have ports for accessing thetransmission channels, with the ports being distributed along an axis ofthe proximal interface. By aligning and engaging the proximal interfacewith a receptacle that traverses the plates or regions of the manifoldassembly, the ports can be quickly and easily sealed to associatedchannels of the various valve/plate modules using a quick-disconnectfitting.

In a first aspect, the invention provides an articulation systemcomprising an articulated structure including an elongate flexible bodyhaving a proximal end and a distal end with an axis therebetween. Aproximal interface adjacent the proximal end has a plurality of ports, aplurality of actuators distal of the ports, and a plurality of lumensextending along the flexible body. Each lumen provides fluidcommunication between an associated port and an associated actuator. Thesystem also includes a manifold having a manifold body. The manifoldbody has a proximal orientation and a distal orientation with a manifoldaxis therebetween. The manifold body has a plurality of regionsdistributed along the manifold axis, each region having a fluid supplychannel. The manifold also has a receptacle that traverses the regions,and the receptacle can removably receive the proximal interface witheach port in sealed fluid communication with an associated fluid supplychannel such that, during use, fluid transmitted from the fluid supplychannels can actuate the actuators and induce movement of the distalend.

In another aspect, the invention provides a manifold for use with anarticulated structure. The articulated structure includes an elongateflexible body extending between a proximal interface and a distal endwith a plurality of ports along the proximal interface, a plurality ofactuators distal of the ports, and a plurality of lumens providing fluidcommunication between the ports and the actuators. The manifoldcomprises a manifold body with a proximal end and a distal end and amanifold axis therebetween. The manifold body has plurality of regionsdistributed along the manifold axis, each region having a fluid channel.A receptacle traverses the regions. The receptacle can removably receivethe proximal portion of the elongate body with each port in sealed fluidcommunication with an associated fluid channel such that, during use,fluid transmitted from the fluid channels can induce movement of thedistal end.

In another aspect, the invention provides an articulated structure foruse with a manifold having a manifold body. The manifold has a pluralityof regions, each region having a fluid channel. The manifold also has areceptacle traversing the regions so that the fluid channels aredistributed along the receptacle. The articulated structure comprises anelongate flexible body having a proximal end and a distal end anddefining an axis therebetween. The body has a proximal interfaceadjacent the proximal end and a plurality of ports along the proximalinterface, a plurality of actuators distal of the ports and along theflexible body, and a plurality of lumens. Each lumen provides fluidcommunication between an associated port and an associated actuator. Theproximal interface of the elongate body is removably receivable by thereceptacle with each port in sealed fluid communication with anassociated supply channel such that, during use, fluid transmitted fromthe fluid supply channels can induce movement of the distal end.

In yet another aspect, the invention provides an interface for use in anarticulation system. The articulation system includes an articulatedstructure with an elongate flexible body having a proximal shaft portionand a distal end and defining an axis therebetween. A plurality oflumens and a plurality of actuators are disposed along the flexiblebody. The proximal shaft portion has a plurality of axially distributedshaft ports, and each lumen provides fluid communication between anassociated shaft port and an associated actuator. The articulationsystem further includes a manifold having a manifold body with aplurality of fluid supply channels. The interface comprises an interfacebody having a proximal end and a distal end, the interface bodycomprising a plurality of deformable seals and a plurality of rigidstructures including a proximal rigid structure and a distal rigidstructure. The rigid structures are axially interleaved with the seals,and passages extend axially within the rigid structures and seals. Thepassages are aligned to form a receptacle extending between the distalrigid structure and the proximal rigid structure. An axial compressionmember couples the proximal rigid structure with the distal rigidstructure so as to maintain an axial compressive force therebetween. Thepassage of the interface body is sized and configured to receive theproximal shaft of the elongate body when the compression member does notapply the axial compressive force. The axial compressive force betweenthe proximal and distal rigid structures can induce protrusion of theseals radially inwardly along the receptacle so as to sealingly engagethe proximal shaft portion between the shaft ports such that, duringuse, fluid transmitted from the fluid supply channels can actuate theactuators and induce movement of the distal end.

In many of the devices and systems described herein, the articulatedstructure comprises a catheter. Other articulated structures that can beused include guidewires, endoscopes and endoscope support devices,boroscopes, industrial manipulators or manipulator portions (such asgrippers or the like), prostheses, and the like. The actuators of thearticulated structures will often include a plurality of balloons, withthe balloons often being included in a balloon array that is distributedaxially and circumferentially about an elongate body of the articulatedstructure. In exemplary embodiments, the number of independent fluidchannels that are coupled through the interface/receptacle pairing willbe between 5 and 60, there typically being from 6 to 50 channels,preferably from 12 to 42 articulation fluid channels, and ideally from12 to 24 articulation fluid channels included within 1-4 extrudedmulti-lumen shafts or other multi-lumen substrate structures.

The manifold body often comprises a plurality of plates. Each plate willtypically have opposed major surfaces, with the regions of the manifoldbody being bordered by the plate surfaces. The receptacle typicallytraverses the plates. Note that the plates of the manifold mayoptionally be included in modular valve/plate units, so that an assemblyof the plates and valves controls and directs fluid flow. In otherembodiments, the manifold may comprise a simple interface structure thatcan, for example, direct fluid between a more complex module assembly(having valves, pressure sensors, and the like) and one or more flexiblemulti-lumen shafts of the articulated body. In other embodiments, theport-supporting proximal interface of the articulable structurecomprises a single rigid contiguous structure. Though the receptacle mayspan across several regions or plates of the manifold assembly, thereceptacle of the assembled manifold often comprises a contiguousfeature such that alignment of the proximal interface with thereceptacle registers all the channels with all the ports. Note thatthere may be additional couplers or connectors that are flexiblyattached to the proximal interface (such as one or more separatelypositionable electrical connector, optical fiber connector, and/orseparate fluid connectors(s) for therapeutic fluids (such as forirrigation, aspiration, drug delivery, or the like) or even actuation(such as for a prosthesis deployment balloon or the like). In otherembodiments, one, some, or all of these connectors may be integratedinto the proximal interface and receptacle. Regardless, one or morequick-disconnect fitting (such as the type that are manually movablebetween a first or latched configuration and a second or detachableconfiguration) may be used to facilitate and maintain sealed fluidcommunication between the ports and associated channels, and to allowquick and easy removal and replacement of the proximal portion so as toreplace the articulated structure with a different alternativearticulated structure.

The proximal interface of the articulatable structure will optionallyfacilitate one or more additional form of communication beyond thesealed port/channel fluid coupling. For example, the proximal interfacemay include a radio frequency identification (RFID) label, an electricalconnector, and/or an optical fiber connector. In such embodiments, thereceptacle will often include an RFID reader, an electrical connector,and/or an optical fiber connector, respectively. RFID data, orelectronic identification data, optical identification data, or otherforms of data can be used by a processor coupled to the manifold toidentify a type of the articulable structure (and optionally thespecific articulable structure itself). Transmitting this identificationdata across such a communication link between the proximal interface andthe receptacle facilitates a plug-and-play operability of the system,allowing a processor of the system to tailor fluid transmissions betweenthe manifold and the articulable structure to the particular type ofarticulable structure that is in use, allowing the system to inducedesired articulations without having to manually reconfigure theprocessor or manifold. Identification data can also help prevent unsafeand inappropriate re-use of high-pressure balloon articulation devices.Articulation state feedback may be provided using electricalinterface/receptacle connectors (such as using known electromagneticinternal navigation systems) or optical interface/receptacle connectors(such as using known optical fiber Bragg grating flex sensors). Suchconnectors may also be used by diagnostic or therapeutic tools carriedby the articulatable structure.

The proximal interface and the receptacle may take any of a variety of(typically corresponding) forms. The receptacle or the proximalinterface may, for example, comprise an array of posts, with the othercomprising an array of indentations. The posts will typically extendalong parallel axes (often from an underlying surface of the proximalinterface) and be matable with the indentations (typically being on thereceptacle), often so that the posts can all be inserted into theindentations with a single movement of a proximal interface body towardthe receptacle. Seals around the posts can provide sealed, isolatedfluid communication between the ports and the channels. The totalcross-sectional area of the posts and indentations that is exposed tothe fluid(s) therein may be limited to less than two square inches, andtypically being less than one square inch, most often being less than0.1 square inches, and ideally being about 0.025 square inches or lessso as to avoid excessive ejection forces. In many such post-indentationembodiments, the articulable structure can transmit the fluid flows fromthe manifold toward the actuators using a multi-lumen shaft. To transmita relatively large number of independent flows, the articulablestructure may have a plurality of multi-lumen shafts, such as an integernumber A of multi-lumen shafts extending distally from the proximalinterface, A being greater than 1 (and typically being 2 or 3). Eachmulti-lumen shaft can have an integer number B of lumens with associatedports and associated actuators, B also being greater than 1 (andtypically being from 3 to 15, more typically being 6 to 15). The arrayof posts may comprise an A×B array of posts, and the post/indentationengagements may be distributed among B valve module plates of themanifold. In exemplary embodiments, each plate comprises a plurality ofplate layers, and each plate has a lateral plate receptacle member thatis affixed to the plate layers. The receptacle can be defined by lateralsurfaces of the receptacle members.

In alternative forms of the proximal interface and receptacle, thereceptacle may be defined by receptacle passages that extend entirelythrough some, most, or even all of the plates of the manifold. Theplates may be stacked into an array (typically with the opposed majorsurfaces in apposition), and the receptacle passages can be axiallyaligned in the assembled manifold so as to facilitate inserting theproximal interface therein. In such embodiments, the proximal interfaceof the articulatable body may comprise a shaft having axiallydistributed ports. Exemplary proximal interface structures may take theform of a simple extruded polymer multi-lumen shaft, with the portscomprising lateral holes drilled into the various lumens. Themulti-lumen shaft itself may be inserted into and seal against thereceptacle, or there may be an intermediate interface body having a tubeor shaft that facilitates the use of the manifold with differentarticulable structures. Regardless, the shaft can be configured andsized to be inserted into the receptacle so as to provide sealingengagement between the ports, and which can result in sealedcommunication between the ports and their associated fluid channels.Optionally, a compression member couples the plates of the manifoldtogether so as to impose axial compression. Deformable seals may bedisposed between the plates, and those seals may protrude radiallyinwardly into the receptacle so as to seal between the ports when thecompression member squeezes the plates together. Alternative sealstructures may protrude radially outwardly to provide sealing against asurrounding surface.

Many of the manifold bodies can make use of a modular manifold assemblystructure having an array of interchangeable plate modules. The platemodules include valves and one or more plate layers. The plate layers ofeach module define a proximal major surface of the module and a distalmajor surface of the plate module. The major surfaces of adjacent platemodules may be in direct apposition with direct plate material-platematerial contact (optionally with the engaging plate surfaces fusedtogether), but may more typically have deformable sealing material (suchas O-rings, formed in place gasket material, laser cut gaskets, 3Dprinted sealing material, or the like) or with a flexible film (such asa flex circuit substrate and/or a deformable sealing member adhesivelybonded to one of the adjoining plates) between the plate structures. Insome embodiments (particularly those in which the plates are laterallysupported by a receptacle member) there may be gaps between some or allof the plates in the array. Regardless, an axial spacing between theports of the proximal interface can correspond to a module-to-moduleseparation between the fluid channels of the adjacent modules. Hence,alignment of the proximal interface with the receptacle can, when theaxes of the interface and the receptacle are aligned, register each ofthe ports with an associated fluid channel (despite the channels beingincluded on different plate modules). Alternative module body structuresmay comprise 3D printed structures, with valves, sensors and the likeoptionally being integrally printed or affixed to the manifold body.

The plate modules will optionally be disposed between a proximal end capof the manifold and a distal end cap of the manifold. The plate modulesmay each include a plurality of plate module layers, with the fluidchannels typically being disposed between the layers (such as by moldingor laser micromachining an open channel into the surface of one layerand sealing the channel by bonding another layer over the open channel).In some embodiments, inflation passages extend through some, most, oreven all of the modular plate layers, and these inflation passages canbe aligned in the stacked plates of the modular manifold assembly toform a continuous inflation fluid header (with the ends of the inflationheader typically being sealed by the end caps). Inflation valves can bedisposed along inflation channels between the inflation header and thereceptacle so as to control a flow of pressurized inflation fluidtransmitted from the header toward a particular port of the articulatedstructure. Optionally, deflation passages may similarly extend throughsome, most, or all of the plate layers and align in the modular manifoldassembly to form a continuous deflation header, deflation valves beingdisposed along deflation channels between the deflation header and thereceptacle. Alternative embodiments may simply port the deflation fluidfrom each plate directly to the atmosphere, foregoing the deflationheader. However, use of the deflation header may be provide advantages;a deflation plenum can be in fluid communication with the deflationheader, and a deflation valve can be disposed between the deflationplenum and a deflation exhaust port (for releasing deflation fluid tothe atmosphere of the like). By coupling a pressure sensor to thedeflation plenum, the deflation back-pressure can be monitored and/orcontrolled.

In most of the manifold assemblies provided herein, a plurality ofpressure sensors are coupled to the channels of the plate modules. Thepressure sensors are also coupled to a processor, and the processortransmits valve commands to valves of the plate modules in response topressure signals from the pressure sensors. Preferably, most or all ofthe channels having an associated port in the articulated assembly willalso have a pressure sensor coupled thereto so as to all the pressuresof fluids passing through the ports of the interface to the monitoredand controlled.

A pressurized canister containing inflation fluid can optionally be usedas the inflation fluid source. The inflation fluid preferably comprisesan inflation liquid in the canister, though the inflation liquid willoften vaporize to an inflation gas for use within the actuators. Thepressurized canister can be mated with a canister receptacle or socketof the manifold so as to transmit the inflation fluid toward the fluidchannels, with the socket often having a pin that pierces a frangibleseal of the canister. The vaporization of liquid in the canister canhelp maintain a constant fluid inflation pressure without having toresort to pumps or the like. An exemplary inflation fluid comprises acryogenic fluid such as nitrous oxide, with the canister preferablycontaining less than 10 oz. of the inflation fluid, often from 0.125 oz.to 7½ oz., typically from 0.25 oz to 3 oz. Fluid pressures in themanifold may range up to about 55 atm. or more, with controlledpressures often being in a range from about 3 atm. to about 40,optionally being less than about 35, and in many cases being about 27atm. or less.

The valve of the fluid control manifolds may include an inflation valvedisposed between the fluid source and a first balloon, and a deflationvalve disposed between a second balloon and a surrounding atmosphere.The first valve can be configured to independently transmit minimumincrements of 50 nl or less of the liquid, with the flowing coolingfluid often remaining liquid till it traverses a throat of the valve.The second valve can be configured to independently transmit at least0.1 scc/s of the gas. Including such valves in the system for inflationlumen of the articulated device may facilitate independent pressurecontrol over the balloons (or the subsets of balloons, with each subsetbeing inflated using a common inflation lumen). The minimum liquidincrement may be 25 nl (or even 15 nl) or less, while the minimum gasflow may be 0.5 scc/s (or even 1 scc/s) or more. Some embodiments mayemploy multi-way valves that can be used to control both inflation fluidflowing into the balloon and deflation fluid exhausted from the balloon,with accuracy of control (despite the different inflation and deflationflows) being maintained by differing valve throats, by differingorifices or other flow restricting devices adjacent the valve, byproportional flow control of sufficient range, and/or by a sufficientlyrapid valve response rate. In some embodiments, a pressure-controlledplenum can be disposed between the fluid source and the first and secondballoon, or the liquid may otherwise vaporize to the gas before thevalve so that none of the liquid transits a valves between the plenumand the balloons.

To facilitate the safe use of inflation fluids for articulation ofcatheters and other articulatable structures, a fluid shutoff valve maybe disposed upstream of the fluid channels. Moreover, a vacuum sourceand a vacuum sensing system may also be included, with the actuatorsbeing disposed within a sealed chamber of the articulation structure andthe vacuum source being coupleable to that chamber. The vacuum sensingsystem can couple the chamber to the shutoff valve so as to inhibittransmission of inflation fluid to the actuators of the articulablestructure in response to deterioration of vacuum within the chamber.Advantageously, the vacuum source may comprise a simple positivedisplacement pump (such as a syringe pump with a latchable handle), andelectronic sensing of the vacuum can provide continuous safetymonitoring. The chamber of the articulatable structure can be providedusing an outer sheath around the balloon array, and optionally an innersheath within a helical or other annular balloon array arrangement. Bysealing the array proximally and distally of the balloons, the spacesurrounding the array can form a vacuum chamber in which the vacuum willdeteriorate if any leakage of the inflation fluid out of the array, andor any leakage of blood, air, or other surrounding fluids into thechamber.

In another aspect, the invention provides an articulation systemcomprising an articulated structure including an elongate flexible bodyhaving a proximal end and a distal end with an axis therebetween. Aproximal interface adjacent the proximal end has a plurality of ports, aplurality of actuators distal of the ports, and a plurality of lumensextending along the flexible body. Each lumen provides fluidcommunication between an associated port and an associated actuator. Thesystem also includes a modular fluid supply assembly, with the assemblycomprising a plurality of plates. Each plate has opposed major surfacesand a fluid supply channel. A receptacle traverses the plates, and thereceptacle can removably receive the proximal interface with each portin sealed fluid communication with an associated fluid supply channelsuch that, during use, fluid transmitted from the fluid supply channelscan actuate the actuators and induce movement of the distal end.

In another aspect, the invention provides a modular fluid supplyassembly for use with an articulated structure. The articulatedstructure includes an elongate flexible body extending between aproximal interface and a distal end (with a plurality of ports along theproximal interface), a plurality of actuators distal of the ports, and aplurality of lumens providing fluid communication between the ports andthe actuators. The modular fluid supply comprises a plurality of plates,each plate having opposed major surfaces and a fluid channel. Areceptacle traverses the plates. The receptacle can removably receivethe proximal portion of the elongate body with each port in sealed fluidcommunication with an associated fluid channel such that, during use,fluid transmitted from the fluid channels can induce movement of thedistal end.

In yet another embodiment, the invention provides a fluid supply systemfor use with a device. The fluid supply system comprises a modular fluidmanipulation assembly comprising a plurality of plate modules. Eachmodule includes a plate having opposed major surfaces, a valve, and afluid channel, the plates in an array having a receptacle traversing theplates. The receptacle removably receives an interface of the device sothat a plurality of ports of the interface are each in sealed fluidcommunication with an associated fluid supply channel of the plates suchthat, during use, fluid transmitted from the fluid supply channels canbe independently transmitted to the ports.

In a yet further embodiment, the invention provides a method forassembling a manifold or interface for use with a device. The device hasan interface with a plurality of ports. The method comprises aligning aplurality of plates in an array. Each plate has opposed major surfaces,a receptacle surface portion extending between the major surfaces, and achannel coupled to the receptacle portion. The receptacle portions areaffixed in alignment so that the receptacle portions form a receptacle.The receptacle is configured to removably receive the device and toprovide sealed fluid communication between the channels and the ports.

In a yet further embodiment, the invention provides a method forpreparing an articulation system for use. The method comprises providingan articulated structure having a proximal interface and a distal endwith a flexible body therebetween. The proximal interface has aplurality of ports with associated actuators disposed along the flexiblebody. The proximal interface is coupled with a receptacle of a modularmanipulator assembly. The manipulator assembly has a plurality of platemodules, each plate module having a plate with opposed major surfaces, afluid channel, and a valve along the channel. The coupling of theproximal interface is performed by aligning the ports with the channelsand sealing between the ports so as to facilitate independent control offluid flow through the ports.

In another aspect, the invention provides an articulation systemcomprising an articulated structure including an elongate flexible bodyhaving a proximal end and a distal end with an axis therebetween. Aproximal interface adjacent the proximal end has a plurality of ports, aplurality of actuators distal of the ports, and a plurality of lumensextending along the flexible body. Each lumen provides fluidcommunication between an associated port and an associated actuator. Amanifold has a manifold body with a plurality of fluid supply channels,the manifold having a receptacle that removably receives the proximalinterface of the articulated structure with each port in sealed fluidcommunication with an associated fluid supply channel such that, duringuse, fluid transmitted from the fluid supply channels can actuate theactuators and induce movement of the distal end, and the fluid can flowfrom the actuators back to the manifold body without mixing of the fluidof different actuators. Optionally, the fluid may comprise a liquid inthe manifold, may vaporize and expand so that the fluid comprises a gasin the actuators, and the gas may flow back to the manifold.

The articulation devices, systems, and methods for articulating elongateflexible structures often have a fluid-driven balloon array that can beused to locally contract a flexible elongate frame or skeleton (forexample, along one or more selected side(s) of one or more selectedaxial segment(s)) of an elongate flexible body so as to help define aresting shape or pose of the elongate body. In preferred embodiments,the skeleton structures described herein will often have pairs ofcorresponding axially oriented surface regions that can move relative toeach other, for example, with the regions being on either side of asliding joint, or coupled to each other by a loop of a deformablehelical coil structure of the skeleton. A balloon of the array (or someother actuator) may be between the regions of each pair. One or more ofthese pairs of surfaces may be separated by an offset that increaseswhen the axis of the skeleton is compressed near the pair. While it iscounterintuitive, axial expansion of the balloon (or another actuator)between such regions can axially contract or shorten the skeleton nearthe balloon, for example, bending the skeleton toward a balloon that isoffset laterally from the axis of the elongate body. Advantageously, theskeleton and balloon array can be configured so that different balloonsapply opposing local axial elongation and contraction forces. Hence,selective inflation of subsets of the balloons and correspondingdeflation of other subsets of the balloons can be used to controllablyurge an elongate flexible body to bend laterally in a desired direction,to change in overall axial length, and/or to do a controlled combinationof both throughout a workspace. Furthermore, varying the inflationpressures of the opposed balloons can controllably and locally modulatethe stiffness of the elongate body, optionally without changing the poseof the articulated elongate body.

In one aspect, the invention provides an articulable catheter comprisingat least one elongate skeleton having a proximal end and a distal endand defining an axis therebetween. The skeleton includes an inner walland an outer wall with a first flange affixed to the inner wall and asecond flange affixed to the outer wall. Opposed major surfaces of thewalls may be oriented primarily radially, and opposed major surfaces ofthe flanges may be oriented primarily axially. A plurality of axialcontraction balloons can be disposed radially between the inner wall andthe outer wall, and axially between the first flange and the secondflange so that, in use, inflation of the contraction balloons pushes thefirst and second flanges axially apart so as to urge an axial overlap ofthe inner and outer walls to increase. This can result in the skeletonadjacent the inflated contraction balloons being locally urged toaxially contract in response to the inflating of the balloon.

In some embodiments, the skeleton comprises a plurality of annular orring structures, often including a plurality of inner rings having theinner walls and a plurality of outer rings having the outer walls. Theflanges of such embodiments may comprise annular flanges affixed to thewalls, and the annular structures or rings may be axially movablerelative to each other. Typically, each ring will include an associatedwall and will have a proximal ring end and a distal ring end, with thewall of the ring affixed to an associated proximal flange at theproximal ring end and to an associated distal flange at the distal ringend, the first and second flanges being included among the proximal anddistal flanges.

In other embodiments, the skeleton comprises at least one helicalmember. For example, the walls may comprise helical walls, and theflanges may comprise helical flanges affixed to the helical walls, thehelical member(s) including the walls and the flanges. The helicalmember may define a plurality of helical loops and the loops may beaxially movable relative to each other sufficiently to accommodatearticulation of the skeleton. Preferably, each loop has an associatedwall with a proximal loop edge and a distal loop edge, the wall beingaffixed to an associated proximal flange at the proximal loop edge andto an associated distal flange at the distal loop edge (the first andsecond flanges typically being included among these proximal and distalflanges).

In the ring embodiments, the helical embodiments, and other embodiments,a plurality of axial extension balloons may be disposed axially betweenadjacent flanges of the skeleton. Typically, only one of the walls ofthe skeleton (for example, an inner wall or an outer wall but not both)may be disposed radially of the extension balloons themselves. In otherwords, unlike many of the contraction balloons, the extension balloonsare preferably not contained radially in a space between an inner walland an outer wall. As a result, and unlike the contraction balloons,inflation of the extension balloons during use will push the adjacentflanges axially apart so as to urge the skeleton adjacent the inflatedextension balloons to locally elongate axially.

Advantageously, the extension balloons and the contraction balloons canbe mounted to the skeleton in opposition so that inflation of theextension balloons and deflation of the contraction balloons locallyaxially elongates the skeleton, and so that deflation of the extensionballoons and inflation of the contraction balloons locally axiallycontracts the skeleton. Note that the balloons can be distributedcircumferentially about the axis so that selective inflation of a firsteccentric subset of the balloons and selective deflation of a secondeccentric subset of the balloons can laterally deflect the axis toward afirst lateral orientation, and so that selective deflation of the firsteccentric subset of the balloons and selective inflation of the secondeccentric subset of the balloons can laterally deflect the axis awayfrom the first lateral orientation. The balloons can also (or instead)be distributed axially along the axis so that selective inflation of athird eccentric subset of the balloons and selective deflation of afourth eccentric subset of the balloons may laterally deflect the axisalong a first axial segment of the skeleton, and selective deflation ofa fifth eccentric subset of the balloons and selective inflation of asixth eccentric subset of the balloons laterally deflects the axis alonga second axial segment of the skeleton, the second axial segment beingaxially offset from the first axial segment.

Most of the systems and devices provided herein, and particularly thosehaving skeletons formed using helical structural members, may benefitfrom groups of the balloons having outer surfaces defined by a sharedflexible tube. The tube may have a cross-section that variesperiodically along the axis, and a multi-lumen shaft can be disposedwithin the flexible tube. The tube may be sealed to the shaftintermittently along the axis, with radial ports extending betweeninteriors of the balloons and a plurality of lumens of the multi-lumenshaft so as to facilitate inflation of selectable subsets of theballoons by directing inflation fluid along a subset of the lumens. Inexemplary embodiments, the inflation fluid may comprise gas within theballoons and liquid within the inflation lumens.

In another aspect, the invention provides an articulable flexible systemcomprising an elongate flexible structural skeleton having a proximalend and a distal end with an axis extending therebetween. The skeletonincludes a plurality of eccentric pairs of surface regions that eachdefine an associated offset between the surface regions of that pair. Aplurality of extension actuators are included, with each extensionactuator coupling the surface regions of an associated pair so thatenergizing of the extension actuator urges local axial elongation of theskeleton. A plurality of contraction actuators may also be provided,with each contraction actuator coupling the surface regions of anassociated pair so that energizing of the contraction actuator urgeslocal axial contraction of the skeleton. The contraction actuators canbe mounted to the skeleton substantially in opposition to the extensionactuators, and an energy supply system can be coupled with the actuatorsso as to simultaneously energize both the extension actuators and thecontraction actuators during use such that an axial stiffness of thearticulable flexible structure can be modulated.

Optionally, the system allows the stiffness to be controllably andselectably increased from a nominal non-energized actuator stiffness toan intermediate stiffness configuration (with the actuators partiallyenergized, and/or to a relatively high stiffness configuration (with theactuators more fully or fully energized). Different axial segments maybe controllably varied (so that a first segment has any of a pluralityof different stiffnesses, and a second segment independently has any ofa plurality of different stiffnesses). In exemplary embodiments, theenergy supply system may comprise a pressurized fluid source and theenergizing of the actuators may comprise pressurizing the actuators (theactuators often comprising fluid-expandable bodies such as balloons orthe like).

In another aspect, the invention provides an articulable flexible devicecomprising an elongate structural skeleton having a proximal end and adistal end with an axis therebetween.

The structural skeleton here includes a helical channel with a proximalchannel boundary and a distal channel boundary. A helical member isaxially movable within the helical channel in correlation with localaxial elongation and contraction of the skeleton (which can facilitateusing the helical member to vary the shape of the skeleton, for example,by pushing helical member axially toward the proximal or distalboundary). A first helical actuation assembly may be disposed within thechannel, the first helical actuation assembly comprising a first helicalfluid conduit with a first plurality of fluid supply channels. The firsthelical actuation assembly may also include a first plurality offluid-expandable bodies in fluid communication with the first channels,and these may be mounted within the channel so as to span between theproximal channel boundary and the helical member (at least wheninflated). A second helical actuation assembly may also be disposedwithin the channel, the second helical actuation assembly comprising asecond helical fluid conduit with a second plurality of fluid supplychannels, along with a second plurality of fluid-expandable bodies influid communication with the second channels. These second fluidexpandable bodies may be positioned in the channel so as to span betweenthe distal channel boundary and the helical member (at least wheninflated) such that axial positioning of the helical member within thechannel is constrained by inflation states of the first and secondplurality of fluid-expandable bodies. The ability to constrain theposition of the helical member within the channel with just the twoballoon arrays (or arrays of other expandable bodies, and rather thanhaving to coordinate inflation and deflation of balloons from a largernumber of separate balloon arrays, such as from three, four, five, oreven six inflation assemblies) can significantly reduce the complexityand improve the performance of the articulation system.

In yet another aspect, the invention provides an articulable flexibledevice comprising an elongate structural skeleton having a proximal endand a distal end with an axis therebetween. The structural skeleton hasa helical member and first and second axial segments between theproximal and distal ends. A helical fluid conduit extends axially alongthe skeleton, the conduit having a first plurality of fluid supplychannels and a second plurality of fluid supply channels. A firstplurality of fluid-expandable bodies is disposed along the first segmentand is coupled with the first fluid supply channels so as to facilitatearticulation of the first segment with a first plurality of degrees offreedom. A second plurality of fluid-expandable bodies is disposed alongthe second segment and is coupled with the second fluid supply channelsso as to facilitate articulation of the second segment with a secondplurality of degrees of freedom. Advantageously, rather than having torely entirely on different conduits for different axial segments (thatprovide, for example, independent degrees of freedom), this aspect ofthe invention allows a common and/or continuous helical conduit to beused for two, three, four, or more segments, typically with each segmentaccommodating multiple degrees of freedom.

In yet another aspect, the invention provides an articulable flexibledevice comprising an elongate structural skeleton having a proximal endand a distal end with an axis therebetween. The structural skeleton hasa helical member and an axial segment between the proximal and distalends. A helical fluid conduit extends axially along the skeleton, theconduit having a plurality of fluid channels. A plurality offluid-expandable bodies are distributed axially and circumferentiallyalong the segment and are coupled to the fluid channels so thatinflation of the balloons during use bends the skeleton along thesegment in first and second transverse lateral bending axes, and alsoaxially elongates the skeleton along the segment so that the segment ofthe skeleton articulates with three degrees of freedom.

Optionally, a first subset of the fluid-expandable bodies can bedisposed substantially axisymmetrical along the segment of the skeletonsuch that inflation of the first subset axially elongates the segment. Asecond subset of the fluid-expandable bodies may be distributedeccentrically along the segment such that inflation of the second subsetlaterally bends the segment along the first lateral bending axis. Athird subset of the fluid-expandable bodies may be distributedeccentrically along the segment such that inflation of the third subsetlaterally bends the segment along the second lateral bending axis andtransverse to the first bending axis. The second and third subsets willoften axially overlap the first subset. Optionally, a fourth subset ofthe fluid-expandable bodies may be supported by the skeletonsubstantially in opposition to the first subset and a fifth subset ofthe fluid-expandable bodies can similarly be substantially in oppositionto the second subset, with a sixth subset of the fluid expandable bodiessubstantially in opposition to the third subset. This can facilitateusing selective inflation of the subsets to controllably and reversiblyarticulate the segment throughout a three-dimensional workspace.

In a still further aspect, the invention provides an articulablestructure comprising an elongate flexible structural skeleton having aproximal end and a distal end with an axis extending therebetween. Theskeleton comprises at least one helical member having a contractionoffset defined between an associated proximally oriented surface and anassociated distally oriented surface. The contraction offset decreaseswith local axial elongation and increases with local axial contractionof the skeleton. A balloon is disposed in the contraction offset suchthat inflation of the balloon increases the offset and urges axialcontraction of the skeleton.

In a still further aspect, the invention provides an articulablestructure comprising an elongate flexible structural skeleton having aproximal end and a distal end with an axis therebetween. The skeletonincludes a first helical member having a first proximally orientedsurface region and a first distally oriented surface region. A secondhelical member has a second proximally oriented surface region and asecond distally oriented surface region. The first and second helicalmembers have an overlap, and a first contraction offset can be definedbetween the first proximally oriented surface region of the first memberand the second distally oriented surface region of the second memberalong the overlap. An extension offset may be defined between the firstdistally oriented surface region of the first helical member and thesecond proximally oriented surface region of the second helical member.A first contraction balloon may be disposed in the first contractionoffset so that inflation of the first contraction balloon urges localaxial contraction of the skeleton. A first extension balloon can bedisposed in the first extension offset and in opposition to the firstballoon so that inflation of the extension balloon urges local axialextension of the skeleton and deflation of the first contractionballoon.

In another aspect, the invention provides an articulation systemcomprising an elongate helical coil having a proximal end and a distalend and defining an axis therebetween. The helical coil has an axialseries of loops. An array of actuation balloons is also included, withat least some of the balloons disposed between a first associated loopand a second associated loop. The second loop may be (or may not be)adjacent the first associated loop. The balloons have a first profileconfiguration, the helical coil being biased so that the loops urge theballoons between the loops toward that first profile configuration. Afluid supply is in fluid communication with the array of balloons so asto expand the balloons axially from the first profile configuration to asecond profile configuration, such that expansion of the balloons urgesthe associated loops of the helical coil apart.

In another aspect, the invention provides an articulation systemcomprising an elongate skeleton having a proximal end and a distal endand defining an axis therebetween. The skeleton can have a plurality ofpairs of interface regions, each pair defining an associated axialoffset between interface surfaces or structures of the pair. The offsetswill typically vary with articulation of the skeleton adjacent theassociated pairs. A fluid supply system may be coupled to the proximalend of the skeleton, and an actuation array may be mounted to theskeleton. The actuation array will optionally include a flexiblesubstrate having opposed major surfaces and a plurality of channelsbetween those surfaces. In some embodiments, the substrate may insteadcomprise a flexible multi-lumen shaft.

Optionally, axial loads of the skeleton adjacent the axial offsets inthe open states can be transmitted by fully expanded non-compliantballoon walls and/or inflation fluid at the full expansion pressure. Inthe closed state the axial loads may be transmitted by solid materialadjacent the axial offsets, optionally being solid material of theskeleton, the balloon wall, or both. Hence, control of the configurationof such systems may be facilitated by a relatively simple digital model(particularly of the commanded configuration), so that a simple digitalvector or matrix (populated by ones and zeros) may be used to describesome or all of the system. Note that more sophisticated computations ofthe kinematics during movement may be appropriate, but these may remainquite manageable through the use of structures and methods that tend toprovide relatively uniform inflation and deflation events, so that theoverall velocities can be correlated to and controlled by simple controlover the timing of opening inflation/deflation valves, etc. Accelerationanalysis may take resilient deformation of the skeleton into account,acceleration-inducing control commands optionally being delayed oravoided when such deformation induces (or are predicted to induce)differences between commanded and offsets that exceed a desiredthreshold. Regardless, the skeleton (and/or structures mounted thereto)will optionally be sufficiently biased to urge the axial offsets to theclosed state.

In yet another system aspect, the invention provides a surgical systemfor use within a body lumen of a patient, the lumen accessible throughan access site. The system comprises an elongate body having a proximalend and a distal end with an axis therebetween, the elongate bodyincluding a first axial segment axially coupled with a second axialsegment. Each axial segment has an associated local lateral stiffness. Afirst actuator can be coupled with the first axial segment and can beconfigured to selectively alter the local lateral stiffness (optionallyby reducing the first local lateral stiffness, and often withoutinducing bending of the first axial segment absent environmental forces)along the first segment in response to a first signal. A length of theelongate body is configured to extend, during use, between the accesssite and the distal end, and that length has a pushability and atrackability. Hence, the first signal can optionally be used to tailorthe pushability and/or trackability of the length of the elongate bodyfor a particular body lumen. In many embodiments, the first actuator isincluded in a plurality of actuators coupled with the elongate body, theplurality including a second actuator coupled with the second axialsegment. The second actuator can be configured to selectively alter thelocal flexibility along the second segment in response to a secondsignal so that the signals can be used to tailor, for the body lumen,the pushability of the length of the elongate body or the trackabilityof the length of the elongate body or both, with the exemplary actuatorscomprising balloons.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified perspective view of a medical procedure in whicha physician can input commands into a catheter system so that a catheteris articulated using systems and devices described herein.

FIG. 1-1 schematically illustrates a catheter articulation system havinga hand-held proximal housing and a catheter with a distal articulatableportion in a relaxed state.

FIGS. 1A-1C schematically illustrate a plurality of alternativearticulation states of the distal portion of the catheter in the systemof FIG. 1.

FIG. 2 schematically illustrates an alternative distal structure havinga plurality of articulatable sub-regions or segments so as to provide adesired total number of degrees of freedom and range of movement.

FIG. 3 is a simplified exploded perspective view showing a balloon arraythat can be formed in a substantially planar configuration and rolledinto a cylindrical configuration, and which can be mounted coaxially toa helical coil or other skeleton framework for use in the catheter ofthe system of FIGS. 1 and 2.

FIGS. 4A and 4B are a simplified cross-section and a simplifiedtransverse cross-section, respectively, of an articulatable catheter foruse in the system of FIG. 1, shown here with the balloons of the arrayin an uninflated, small axial profile configuration and between loops ofthe coil.

FIG. 4C is a simplified transverse cross-section of the articulatablecatheter of FIGS. 4A and 4B, with a plurality of axially alignedballoons along one side of the articulatable region of the catheterinflated so that the catheter is in a laterally deflected state.

FIG. 4D is a simplified transverse cross-section of the articulatablecatheter of FIG. 4, with a plurality of laterally opposed balloonsinflated so that the catheter is in an axially elongated state.

FIG. 5 schematically illustrates components for use in the cathetersystem of FIG. 1, including the balloon array, inflation fluid source,fluid control system, and processor.

FIG. 5A is a simplified schematic of an alternative balloon array andfluid control system, in which a plurality of valves coupled with theproximal end of the catheter can be used to direct fluid to any of aplurality of channels of the array and thereby selectably determine asubset of balloons to be expanded.

FIGS. 5B and 5C schematically illustrate simplified multi-layeredballoon array substrates defining channels, associated fluid controlvalves, and valve-control leads or channels, for use in the cathetersystem of FIG. 5.

FIGS. 6A and 6B are simplified transverse cross-sections of alternativearticulatable catheter structures having a balloon array substratedisposed radially outwardly from a helical coil skeleton, and having aballoon array substrate disposed radially between inner and outerhelical coils, respectively.

FIG. 6C is a simplified transverse cross-section of an articulatablecatheter for use in the system of FIG. 1, wherein balloons each radiallyengage a plurality of loops of a helical coil of a catheter skeleton soas to inhibit bending of a catheter axis.

FIG. 6D is a schematic of a balloon array and valve system for use inthe catheter of FIG. 6C so as to selectably and locally inhibit bendingalong one or more desired axial portion of the catheter.

FIGS. 6E-6H are schematic illustrations showing exemplary balloon arraystructures and interactions between balloons and other components ofexemplary assemblies for selectively and locally stiffening flexiblecatheters and other elongate bodies.

FIGS. 6I and 6J are a simplified plan schematic and perspectiveillustration, respectively, showing an alternative actuation arraystructure having tabs that can be displaced radially from a cylindricalsubstrate surface shape, and with balloons on the tabs.

FIG. 6K is a simplified transverse cross-section of an alternativecatheter structure having material or a body disposed between a balloonand a helical surface so as to provide desirable interface surfaceshapes, and also shows a sheath to radially contain any releasedinflation fluid and/or to apply an axially compressive load to theskeleton and balloons.

FIG. 6L is a simplified transverse cross-section of yet anotheralternative catheter structure in which the skeleton includesreceptacles for receiving expandable bodies therein so as to inhibitrelative migration between the expandable bodies and skeleton, and tounintended axial deflections; and also shows a pull wire to activelyapply controllable axial loads to the skeleton and balloons.

FIGS. 6M-6P schematically illustrate exemplary balloons, balloon arraystructures, and methods for making balloon arrays for use in thearticulation and/or stiffening systems described herein.

FIGS. 7A-7F schematically illustrate valve and balloon arrangementswhich may be used and/or combined in the inflation fluid supply systemsof the systems and devices described herein.

FIGS. 7G-7I schematically illustrate a simple alternative balloon arraystructure in which the substrate is coiled helically, and in whichballoons and channels are formed separately and affixed between layersof the substrate.

FIG. 8 schematically illustrates a catheter articulation system in whichan input of the system is incorporated with an introducer sheath.

FIG. 9 shows a helical coil with inflated and uninflated balloons of aballoon array, with a distal portion of the coil removed to show thediffering lateral orientations of the balloons relative to the axis ofthe coil.

FIGS. 10A-10D are perspective drawings showing an exemplary flat-patternsubstrate and associated balloon array generated by unwinding a helicalballoon pattern, along with an exemplary bonded balloon fabricationtechnique.

FIG. 10E illustrates an alternative bonded balloon arrangement.

FIGS. 10E-10I schematically illustrate balloon structures andfabrication techniques for use in the balloon arrays described herein.

FIGS. 11A and 11B schematically illustrate balloon arrays in which theballoons are disposed over multi-lumen helical coil cores, shafts, orconduits, and also show the effects of varying balloon inflation densityon a radius of curvature of a catheter or other flexible body.

FIGS. 11C and 11D schematically illustrate structures having a pluralityof interleaved coaxial helical coils.

FIGS. 11E-11G schematically illustrate balloons disposed over a helicalcore at differing lateral orientations, and also show how extrudedand/or micromachined multi-lumen helical cores can be used to providefluid communication between and/or inflate one or more associatedballoons at desired lateral orientations on a common core.

FIG. 12 is an exploded view of components that may be included in anarticulated segment of an elongate articulated body, with the componentslaterally offset from their assembled position.

FIG. 13 schematically illustrates bending of a diagnosis or treatmentdelivery catheter into alignment with a target tissue by actuating aplurality of articulation sub-portions or segments of the catheter.

FIGS. 13A-13C schematically illustrate an exemplary multi-lumen cablestructure having an integrated stiffening balloon, a multi-lumen helicalcore structure, and a transition between a helical core and thinmulti-channel fluid transmission cable, respectively.

FIGS. 14A-14C illustrate components of an alternative embodiment havinga plurality of interleaved multi-lumen polymer helical cores interleavedwith a plurality of resilient coil structures having axially orientedsurfaces configured to radially restrain the balloons.

FIG. 15 is a perspective view of an alternative helical balloon corehaving a radially elongate cross-section to limit inflation fluid flowsand provide additional fluid channels and/or channel sizes.

FIG. 16 is a perspective view showing an exemplary introducersheath/input assembly having a flexible joystick for receiving movementcommands using relative movement between hands or fingers of a user.

FIGS. 17A and 17B are a perspective view and a cross-section ofcomponents of a catheter and fluid supply manifold system.

FIG. 17C is a perspective view of a fluid supply manifold havingcomponents similar to those of FIGS. 17A and 17B, showing how additionalinterchangeable modules can be included in the manifold assembly forcontrolling fluid systems having greater numbers of fluid channels.

FIG. 18 is a simplified schematic of a modular manifold having a stackof valve plate assemblies through which a multi-lumen connector extendsso as to provide controlled fluid flow to and from balloons of an array.

FIGS. 18A-18C are perspective views showing an alternative modularmanifold assembly having modules that each include valves, supply fluidchannels, exhaust fluid channels, and passages through the plates of themodules that align in the stacked-plate assembly for use as multi-lumenshaft receptacles, fluid headers, and the like.

FIGS. 18D and 18E are alternative simplified schematics of modular fluidmanifold systems showing additional components and systems that can becombined with those of FIG. 18.

FIGS. 18F and 18G illustrate an interface for coupling any of aplurality of alternative multi-lumen shafts having differing sizesand/or shapes to a stacked-plate fluid manifold assembly.

FIG. 19 is a perspective view of a modular manifold with the layers ofone of the valve assemblies exploded so as to show the associatedvalves, axial passages, and lateral channels.

FIGS. 19A and 19B are a simplified perspective view and a schematiccross-section of plate layers used in a modular manifold similar to thatof FIG. 19, showing channels and passages for one of multi-lumensshafts.

FIGS. 20A-22A schematically illustrate skeletons structures havingframes or members with balloons mounted in opposition so as to axiallyextend with inflation of one subset of the balloons, and to axiallycontract with inflation of another subset of balloons.

FIGS. 22B and 22C are a schematic illustration of an exemplary axialexpansion/contraction skeleton with axial expansion and axialcontraction balloons; and a corresponding cross-section of a skeletonhaving an axial series of annular members or rings articulated by theaxial expansion and axial contraction balloons, respectively.

FIGS. 22D-22H are illustrations of elongate flexible articulatedstructures having annular skeletons with three opposed sets of balloons,and show how varying inflation of the balloons can be used to axiallycontract some portions of the frame and axially extend other portions tobend or elongate the frame and to control a pose or shape of the framein three dimensions.

FIGS. 23A-23J are illustrations of alternative elongate articulatedflexible structures having annular skeletons and two sets of opposedballoons, and show how a plurality of independently controllable axialsegments can be combined to allow control of the overall elongatestructure with 6 or more degrees of freedom.

FIGS. 24A-24G illustrate components of another alternative elongatearticulated flexible structure having axial expansion balloons andopposed axial contraction balloons, the structures here having helicalskeleton members and helical balloon assemblies.

FIGS. 25A-25F illustrate exemplary elongate articulated flexiblestructures having helical skeleton members and three helical balloonassemblies supported in opposition along the skeleton, and also show howselective inflation of subsets of the balloons can locally axiallyelongate and/or contract the skeleton to bend the structure laterallyand/or alter the overall length of the structure.

FIGS. 26A and 26B illustrate alternative articulated structures similarto those of FIGS. 25A-25F, here with two balloon assemblies supported inopposition along the frames.

FIG. 27 illustrates alternative multi-lumen conduit or core structuresfor use in the balloon assemblies of FIGS. 24 and 25, showing a varietyof different numbers of channels that can be used with different numbersof articulated segments.

FIG. 28 schematically illustrates control system logic for using thefluid drive systems described herein to articulate catheters and otherelongate flexible structures per input provided by a system user.

FIG. 29 schematically illustrates a data acquisition and processingsystem for use within the systems and methods described herein.

FIGS. 30A-30D illustrate an alternative interface for coupling a modularfluid manifold to a plurality of multi-lumen shafts so as to providecontrol over articulation of a catheter along a plurality of segments,each having a plurality of degrees of freedom, along with portions ofsome of the plate modules of the manifold, with the plate modules herehaving a receptacle member that helps couple the layers of the plates toposts of the interface.

FIGS. 31A-31E illustrate an alternative articulatable structure having asingle multi-lumen core with balloons extending eccentrically from thecore, along with details of the structure's components and assembly.

FIGS. 32A and 32B illustrate a still further alternative articulatablestructure having a frame that may be formed using laterally cuts in apolymer tube, by 3D printing, or the like.

FIGS. 33A and 33B schematically illustrate alternative inflatableballoon actuators and associated mechanisms that can rotate a distalsheath or other structure about an axis of a catheter or anotherarticulatable structure.

FIGS. 34A and 34B schematically illustrate a reciprocating balloon andframe assembly for incrementally moving a sheath or other structureadjacent the distal end of an articulated structure proximally ordistally.

FIGS. 35A and 35B schematically illustrate an alternative balloon andframe arrangement for incrementally moving a sheath or other structureadjacent the distal end of an articulated structure proximally and/ordistally.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally provides fluid control devices, systems,and methods that are particularly useful for articulating catheters andother elongate flexible structures. In exemplary embodiments theinvention provides a modular manifold architecture that includesplate-mounted valves to facilitate fluid communication along a pluralityof fluid channels included in one or more multi-lumen shafts, often forarticulating actuators of a catheter. Preferred actuators includeballoons or other fluid-expandable bodies, and the modular manifoldassemblies are particularly well suited for independently controlling arelatively large number of fluid pressures and/or flows. The individualplate modules may include valves that control fluid supplied to acatheter or other device, and/or fluid exhausted from the catheter orother device. A receptacle extending across a stack of such modules canreceive a fluid flow interface having a large number of individual fluidcoupling ports, with the total volume of the modular valve assembly,including the paired receptacle and fluid flow interface of the deviceoften being quite small. In fact, the modular manifold will preferablybe small enough to hold in a single hand, even when a controller (suchas a digital processor), a pressurized fluid source (such as a canisterof cryogenic fluid), and an electrical power source (such as a battery)are included. When used to transmit liquids that will vaporize to a gasthat inflates a selected subset of microballoons within a microballoonarray, control over the small quantities of inflation liquids may directmicrofluidic quantities of inflation fluids. Microelectromechanicalsystem (MEMS) valves and sensors may find advantageous use in thesesystems; fortunately, suitable microfluidic and MEMS structures are nowcommercially available and/or known valve structures may be tailored forthe applications described herein by a number of commercial serviceproviders and suppliers.

Embodiments provided herein may use balloon-like structures to effectarticulation of the elongate catheter or other body. The term“articulation balloon” may be used to refer to a component which expandson inflation with a fluid and is arranged so that on expansion theprimary effect is to cause articulation of the elongate body. Note thatthis use of such a structure is contrasted with a conventionalinterventional balloon whose primary effect on expansion is to causesubstantial radially outward expansion from the outer profile of theoverall device, for example to dilate or occlude or anchor in a vesselin which the device is located. Independently, articulated medialstructures described herein will often have an articulated distalportion, and an unarticulated proximal portion, which may significantlysimplify initial advancement of the structure into a patient usingstandard catheterization techniques.

The catheter bodies (and many of the other elongate flexible bodies thatbenefit from the inventions described herein) will often be describedherein as having or defining an axis, such that the axis extends alongthe elongate length of the body. As the bodies are flexible, the localorientation of this axis may vary along the length of the body, andwhile the axis will often be a central axis defined at or near a centerof a cross-section of the body, eccentric axes near an outer surface ofthe body might also be used. It should be understood, for example, thatan elongate structure that extends “along an axis” may have its longestdimension extending in an orientation that has a significant axialcomponent, but the length of that structure need not be preciselyparallel to the axis. Similarly, an elongate structure that extends“primarily along the axis” and the like will generally have a lengththat extends along an orientation that has a greater axial componentthan components in other orientations orthogonal to the axis. Otherorientations may be defined relative to the axis of the body, includingorientations that are transverse to the axis (which will encompassorientation that generally extend across the axis, but need not beorthogonal to the axis), orientations that are lateral to the axis(which will encompass orientations that have a significant radialcomponent relative to the axis), orientations that are circumferentialrelative to the axis (which will encompass orientations that extendaround the axis), and the like. The orientations of surfaces may bedescribed herein by reference to the normal of the surface extendingaway from the structure underlying the surface. As an example, in asimple, solid cylindrical body that has an axis that extends from aproximal end of the body to the distal end of the body, the distal-mostend of the body may be described as being distally oriented, theproximal end may be described as being proximally oriented, and thesurface between the proximal and distal ends may be described as beingradially oriented. As another example, an elongate helical structureextending axially around the above cylindrical body, with the helicalstructure comprising a wire with a square cross section wrapped aroundthe cylinder at a 20 degree angle, might be described herein as havingtwo opposed axial surfaces (with one being primarily proximallyoriented, one being primarily distally oriented). The outermost surfaceof that wire might be described as being oriented exactly radiallyoutwardly, while the opposed inner surface of the wire might bedescribed as being oriented radially inwardly, and so forth.

Referring first to FIG. 1, a first exemplary catheter system 1 andmethod for its use are shown. A physician or other system user Uinteracts with catheter system 1 so as to perform a therapeutic and/ordiagnostic procedure on a patient P, with at least a portion of theprocedure being performed by advancing a catheter 3 into a body lumenand aligning an end portion of the catheter with a target tissue of thepatient. More specifically, a distal end of catheter 3 is inserted intothe patient through an access site A, and is advanced through one of thelumen systems of the body (typically the vasculature network) while userU guides the catheter with reference to images of the catheter and thetissues of the body obtained by a remote imaging system.

Exemplary catheter system 1 will often be introduced into patient Pthrough one of the major blood vessels of the leg, arm, neck, or thelike. A variety of known vascular access techniques may also be used, orthe system may alternatively be inserted through a body orifice orotherwise enter into any of a number of alternative body lumens. Theimaging system will generally include an image capture system 7 foracquiring the remote image data and a display D for presenting images ofthe internal tissues and adjacent catheter system components. Suitableimaging modalities may include fluoroscopy, computed tomography,magnetic resonance imaging, ultrasonography, combinations of two or moreof these, or others.

Catheter 3 may be used by user U in different modes during a singleprocedure, including two or more of a manual manipulation mode, anautomated and powered shape-changing mode, and a combination mode inwhich the user manually moves the proximal end while a computerarticulates the distal portion. More specifically, at least a portion ofthe distal advancement of catheter 3 within the patient may be performedin a manual mode, with system user U manually manipulating the exposedproximal portion of the catheter relative to the patient using hands H1,H2. Catheter 3 may, for example, be manually advanced over a guidewire,using either over-the-wire or rapid exchange techniques. Catheter 3 mayalso be self-guiding during manual advancement (so that for at least aportion of the advancement of catheter 3, a distal tip of the cathetermay guide manual distal advancement). Automated lateral deflection of adistal portion of the catheter may impose a desired distal steering bendprior to a manual movement, such as near a vessel bifurcation, followedby manual movement through the bifurcation. In addition to such manualmovement modes, catheter system 1 may also have a 3-D automated movementmode using computer controlled articulation of at least a portion of thelength of catheter 3 disposed within the body of the patient to changethe shape of the catheter portion, often to advance or position thedistal end of the catheter. Movement of the distal end of the catheterwithin the body will often be provided per real-time or near real-timemovement commands input by user U, with the portion of the catheter thatchanges shape optionally being entirely within the patient so that themovement of the distal portion of the catheter is provided withoutmovement of a shaft or cable extending through the access site. Stillfurther modes of operation of system 1 may also be implemented,including concurrent manual manipulation with automated articulation,for example, with user U manually advancing the proximal shaft throughaccess site A while computer-controlled lateral deflections and/orchanges in stiffness over a distal portion of the catheter help thedistal end follow a desired path or reduce resistance to the axialmovement.

Referring next to FIG. 1-1 components which may be included in or usedwith catheter system 1 or catheter 3 (described above) can be more fullyunderstood with reference to an alternative catheter system 10 and itscatheter 12. Catheter 12 generally includes an elongate flexiblecatheter body and is detachably coupled to a handle 14, preferably by aquick-disconnect coupler 16. Catheter body 12 has an axis 30, and aninput 18 of handle 14 can be moved by a user so as to locally alter theaxial bending characteristics along catheter body 12, often for variablyarticulating an actuated portion 20 of the catheter body. Catheter body12 will often have a working lumen 26 into or through which atherapeutic and/or diagnostic tool may be advanced from a proximal port28 of handle 14. Alternative embodiments may lack a working lumen, mayhave one or more therapeutic or diagnostic tools incorporated into thecatheter body near or along actuated portion 20, may have a sufficientlysmall outer profile to facilitate use of the body as a guidewire, maycarry a tool or implant near actuated portion 20 or near distal end 26,or the like. In particular embodiments, catheter body 12 may support atherapeutic or diagnostic tool 8 proximal of, along the length of,and/or distal of actuated portion 20. Alternatively, a separate elongateflexible catheter body may be guided distally to a target site oncecatheter body 20 has been advanced (with the elongate body for such usesoften taking the form and use of a guidewire or guide catheter).

The particular tool or tools included in, advanceable over, and/orintroducible through the working lumen of catheter body 20 may includeany of a wide range of therapeutic and/or treatment structures. Examplesinclude cardiovascular therapy and diagnosis tools (such as angioplastyballoons, stent deployment balloons or other devices, atherectomydevices, tools for detecting, measuring, and/or characterizing plaque orother occlusions, tools for imaging or other evaluation of, and/ortreatment of, the coronary or peripheral arteries, structural hearttools (including prostheses or other tools for valve procedures, foraltering the morphology of the heart tissues, chambers, and appendages,and the like), tools for electrophysiology mapping or ablation tools,and the like); stimulation electrodes or electrode implantation tools(such as leads, lead implant devices, and lead deployment systems,leadless pacemakers and associated deployments systems, and the like);neurovascular therapy tools (including for accessing, diagnosis and/ortreatment of hemorrhagic or ischemic strokes and other conditions, andthe like); gastrointestinal and/or reproductive procedure tools (such ascolonoscopic diagnoses and intervention tools, transurethral proceduretools, transesophageal procedure tools, endoscopic bariatric proceduretools, etc.); hysteroscopic and/or falloposcopic procedure tools, andthe like; pulmonary procedure tools for therapies involving the airwaysand/or vasculature of the lungs; tools for diagnosis and/or treatment ofthe sinus, throat, mouth, or other cavities, and a wide variety of otherendoluminal therapies and diagnoses structures. Such tools may make useof known surface or tissue volume imaging technologies (includingimaging technologies such as 2-D or 3-D cameras or other imagingtechnologies; optical coherence tomography technologies; ultrasoundtechnologies such as intravascular ultrasound, transesophogealultrasound, intracardiac ultrasound, Doppler ultrasound, or the like;magnetic resonance imaging technologies; and the like), tissue or othermaterial removal, incising, and/or penetrating technologies (such arotational or axial atherectomy technologies; morcellation technologies;biopsy technologies; deployable needle or microneedle technologies;thrombus capture technologies; snares; and the like), tissue dilationtechnologies (such as compliant or non-compliant balloons, plasticallyor resiliently expandable stents, reversibly expandable coils, braids orother scaffolds, and the like), tissue remodeling and/or energy deliverytechnologies (such as electrosurgical ablation technologies, RFelectrodes, microwave antennae, cautery surfaces, cryosurgicaltechnologies, laser energy transmitting surfaces, and the like), localagent delivery technologies (such as drug eluting stents, balloons,implants, or other bodies; contrast agent or drug injection ports;endoluminal repaving structures; and the like), implant and prosthesisdeploying technologies, anastomosis technologies and technologies forapplying clips or sutures, tissue grasping and manipulationtechnologies; and/or the like. In some embodiments, the outer surface ofthe articulation structure may be used to manipulate tissues directly.Other examples of surgical interventions which can impose significantcollateral damage, and for which less-invasive endoluminal approachesmay be beneficial, include treatments of the brain (including nervestimulation electrode implantation, neurovascular therapies includingfor diagnosis and/or treatment of hemorrhagic or ischemic strokes andother conditions, and the like); cardiovascular therapies and diagnoses(including evaluation and/or treatments of the coronary or peripheralarteries, structural heart therapies such as valve procedures or closureof atrial appendages, electrophysiology procedures such as mapping andarrhythmia treatments, and the like); gastrointestinal and/orreproductive procedures (such as colonoscopic diagnoses andinterventions, transurethral procedures, transesophageal procedures,endoscopic bariatric procedures, etc.); hysteroscopic and/orfalloposcopic procedures, and the like; pulmonary procedures involvingthe airways and/or vasculature of the lungs; diagnosis and/or treatmentof the sinus, throat, mouth, or other cavities, and a wide variety ofother endoluminal therapies and diagnoses. Unfortunately, knownstructures used for different therapies and/or insertion into differentbody lumens are quite specialized, so that it will often beinappropriate (and possibly ineffective or even dangerous) to try to usea device developed for a particular treatment for another organ system.Non-medical embodiments may similarly have a wide range of tools orsurfaces for industrial, assembly, imaging, manipulation, and otheruses.

Addressing catheter body 12 of system 10 (and particularly articulationcapabilities of actuated portion 20) in more detail, the catheter bodygenerally has a proximal end 22 and a distal end 24 with axis 30extending between the two. As can be understood with reference to FIG.2, catheter body 12 may have a short actuated portion 20 of about 3diameters or less, but will often have an elongate actuated portion 20extending intermittently or continuously over several diameters of thecatheter body (generally over more than 3 diameters, often over morethan 10 diameters, in many cases over more than 20 diameters, and insome embodiments over more than 40 diameters). A total length ofcatheter body 12 (or other flexible articulated bodies employing theactuation components described herein) may be from 5 to 500 cm, moretypically being from 15 to 260 cm, with the actuated portion optionallyhaving a length of from 1 to 150 cm (more typically being 2 to 20 cm)and an outer diameter of from 0.65 mm to 5 cm (more typically being from1 mm to 2 cm). Outer diameters of guidewire embodiments of the flexiblebodies may be as small as 0.012″ though many embodiments may be morethan 2 Fr, with catheter and other medical embodiments optionally havingouter diameters as large as 34 French or more, and with industrialrobotic embodiments optionally having diameters of up to 1″ or more.Exemplary catheter embodiments for structural heart therapies (such astrans-catheter aortic or mitral valve repair or implantation, leftatrial appendage closure, and the like) may have actuated portions withlengths of from 3 to 30 cm, more typically being from 5 to 25 cm, andmay have outer profiles of from 10 to 30 Fr, typically being from 12 to18 Fr, and ideally being from 13 to 16 Fr. Electrophysilogy therapycatheters (including those having electrodes for sensing heart cyclesand/or electrodes for ablating selected tissues of the heart) may havesizes of from about 5 to about 12 Fr, and articulated lengths of fromabout 3 to about 30 cm. A range of other sizes might also be implementedfor these or other applications.

Referring now to FIGS. 1A, 1B, and 1C, system 10 may be configured toarticulate actuated portion 20. Articulation will often allow movementcontinuously throughout a range of motion, though some embodiments mayprovide articulation in-part or in-full by selecting from among aplurality of discrete articulation states. Catheters having opposedaxial extension and contraction actuators are described herein that maybe particularly beneficial for providing continuous controlled andreversible movement, and can also be used to modulate the stiffness of aflexible structure. These continuous and discrete systems share manycomponents (and some systems might employ a combination of bothapproaches).

First addressing the use of a discrete state system, FIG. 1A, system 10can, for example, increase an axial length of actuated portion 20 by oneor more incremental changes in length ΔL. An exemplary structure forimplementation of a total selectable increase in length ΔL can combine aplurality of incremental increases in length ΔL=ΔL₁+ΔL₂+ . . . ), as canbe understood with reference to FIG. 4D. As shown in FIGS. 1B and 1C,system 10 may also deflect distal end 24 to a first bent state having afirst bend angle 31 between unarticulated axis 30 and an articulatedaxis 30′ (as shown schematically in FIG. 1B), or to a second bent statehaving a total bend angle 33 (between articulated axis 30 andarticulated axis 30″), with this second bend angle being greater thanthe first bend angle (as shown schematically in FIG. 1C). An exemplarystructure that could optionally be used by combining multiple discretebend angle increments to form a total bend angle 33 (and/or which couldalso provide continuous movement) can be understood with reference toFIG. 4C. Regardless, the additional total cumulative bend angle 33 mayoptionally be implemented by imposing the first bend 31 (of FIG. 1B) asa first increment along with one or more additional bend angleincrements 35. The incremental changes to actuated portion 20 may beprovided by fully inflating and/or deflating actuation balloons of thecatheter system. In fact, some embodiments could even be capable of onlya single bend and/or elongation increment, but would more often havesignificantly more incremental articulation state options beyond thoseshown in FIGS. 1A-1C (and still more often would provide bendingthroughout a continuous range), so that a number of bend angles, bendorientations, axial lengths, and the like can and will often beavailable. For example, system 10 may be configured to provide any of aplurality of discrete alternative total bend angles (often being 3 ormore, 5 or more, 10 or more, 20 or more, or even 40-100 angles, withembodiments providing between 3 and 20 alternative bend angles in agiven lateral orientation), with one of the alternative bend anglestypically comprising a resting or unarticulated angle (optionally beingstraight or having a zero degree bend angle; alternatively having somepreset or physician-imposed bend). Incremental or continuous bendcapabilities may be limited to a single lateral orientation, but willmore typically be available in different lateral orientations, mosttypically in any of 3 or 4 orientations (for example, using balloonspositioned along two pairs of opposed lateral axes, sometimes referredto as the +X, −X, +Y and −Y orientations), and by combining differentbend orientations, in intermediate orientations as well. Continuouspositioning may be implemented using similar articulation structures bypartially inflating or deflating balloons or groups of balloons.

System 10 may also be configured to provide catheter 12 with any of aplurality of discrete alternative total axial lengths. As with the bendcapabilities, such length actuation may also be implemented by inflatingballoons of a balloon array structure. To provide articulation with thesimple balloon array structures described herein, each actuation may beimplemented as a combination of discrete, predetermined actuationincrements (optionally together with one or more partial or modulatedactuation) but may more often be provided using modulated or partialinflation of some, most, or all of the balloons. Hence, regardless ofwhether or not a particular catheter includes such bend-articulationcapabilities, system 10 may be configured to provide catheter 12 with atleast any of a plurality of discrete alternative total axial lengths(often being 3 or more, 5 or more, 10 or more, 20 or more, or even40-100 lengths, with most embodiments providing between 3 and 20alternative total lengths), more typically providing lengths throughoutan elongation range. Nonetheless, embodiments of system 10 can beconfigured to implement each total actuation, in-part or in-full, as acombination of discrete, predetermined actuation increments. Some or allof the discrete actuation increments (and the associated balloon(s)) mayhave an associated location 37 or length segment along axis 30 withinactuated portion 20, optionally an associated lateral X-Y orientation,and/or an associated predetermined incremental actuation amount. Thelateral X-Y orientation of at least some of the actuation increments maybe transverse to the local axis of catheter body 12 (shown as the Z axisin FIG. 1B) and the relationship between the positions of the variousactuation balloons 36 and the lateral deflection axes X-Y can beunderstood with reference to FIG. 4. Regarding the incremental actuationamount, inflation and/or deflation of a particular balloon may becharacterized using an incremental bend angle, an axial offset change,axial elongation displacement, and/or the like. Each actuation increment(including inflation or deflation of one or more balloon) may also havean associated increment actuation time (for full inflation or deflationof the balloon, with these often being different). While these times maybe variably controlled in some embodiments, optionally with controlledvariations in fluid flow (such as ramp-up or ramp downs) during a singleactuation increment, many embodiments may instead use relatively uniformincremental actuation pressures and flow characteristics (optionally viafixed throttled or damped fluid flows into and/or out of the balloons).Nonetheless, controllable (and relatively high) overall distalvelocities may be provided from coordinated timing of the discreteactuation increments along the length of the catheter body, for example,by controlled initiating of inflation of multiple balloons so that atleast a portion of their associated inflation times overlap. Anactuation increment implementation structure (generally one or moreassociated actuation balloons) can be associated with each actuationincrement, with the actuation structure optionally being commanded to bein either an actuated configuration or an unactuated configuration (suchas with the actuation balloon being fully inflated or fully deflated,respectively). Varying of the bend angles may, for example, beimplemented by changing the number of balloons along one side of thecatheter body 12 that are commanded to be fully inflated at a giventime, with each additional balloon inflation incrementally increasingthe overall bend angle. The balloons will often have differingassociated axial locations 37, 37′ along actuated portion 20. This canallow the axial location of a commanded bend increment to be selectedfrom among a plurality of discrete axial locations 37, 37′ by selectionof the associated balloon axial locations to be included in the inflatedgroup, which will typically be less than all of the balloons in anarray. Desired total actuations can be implemented by identifying andcombining a sub-set of bend increments (and/or other actuationincrements) from among the available incremental actuations andinflating the associated sub-set of actuation balloons from among theoverall balloon array or arrays). Hence, along with allowing controlover the total bend angle, appropriate selection of the sub-set fromamong the pre-determined bend increments along actuated portion 20 mayallow control over an average radius of the bend, for example, byaxially distributing or separating the subset of discrete bendincrements over an overall length of the bend. Control over an axiallocation of the overall bend can be provided by selecting the axiallocations of the inflated balloon subset; and control over the lateralX-Y orientation of the total bend can be provided by selecting thesubset from among the differing available incremental lateralorientations so as to combine together to approximate a desiredorientation; and the like.

As suggested above, actuated portion 20 can often be articulated intoany of a plurality of different overall bend profiles with a pluralityof differing bend angles. Additionally, and often substantiallyindependently of the bend angle, actuated portion 20 can be reconfiguredso as to bend in any of a plurality of differing lateral bend directions(in the cross-sectional or X-Y plane, often through a combination ofdiscrete incremental bend orientations), can bend at any of a pluralityof axial locations, and/or can be actuated to bend with any of aplurality of differing overall bend radii. Furthermore, the bendorientation and/or bend radius may controllably differ along the axiallength of actuated portion 20. Interestingly, and contrary to mostcatheter steering systems, some embodiments of the present invention maynot be capable of driving axis 30 of catheter body 20 to intermediatebend angles between sums of the discrete bend increments 31, 35, astotal articulation may be somewhat digital in nature. Note, however,that while some or all of the actuation increments may be uniform, theindividual bend angles and the like may alternatively be non-uniform(such as by including balloons of different sizes within the array), sothat a subset of the pre-determined bend increments can be configured toallow fine-tuning of bend angle and the like. Alternatively, as totalactuation will often be a sum of a series of incremental actuations, oneor more balloons can be configured to provide analog (rather thandigital) articulation, with the analog movement often being sufficientto bridge between discrete digital articulations and thereby providing acontinuous position range. This can be implemented, for example, byconfiguring the system to variably partially inflate one or more of theballoons of the array (rather than relying on full inflation ordeflation) such as by using an associated positive displacement pump.Still more commonly, balloons or groups of balloons may be inflated tovariable pressures throughout a range, providing effectively analogmovement throughout the range of motion of the system.

Conveniently, the overall actuation configuration or state of catheterbody 12 may be described using a plurality of scalar quantities that areeach indicative of the states of associated actuation increments andballoons, with those incremental states optionally being combined todefine an actuation state vector or matrix. Where the actuationincrements are digital in nature (such as being associated with fullinflation or full deflation of a balloon), some or all of the actuationstate of catheter 12 may be described by a digital actuation statevector or matrix. Such digital embodiments (particularly those withoutanalog components) may take advantage of these simple digital statevectors or digital state matrices to significantly facilitate datamanipulations and enhance control signal processing speeds, helping tolessen minimum desired processing capabilities and overall system costs.Note also that many of the resolution, flexibility, and accuracyadvantages of the balloon array systems described above are alsoavailable when all of the balloons of the array are inflatable tovariable inflation states. Hence, some embodiments of the systemsdescribed herein may include fluid control systems that direct modulatedquantities and/or pressures of fluids to multiple balloons along one ormore fluid transmission channels. Control systems for such embodimentsmay employ similar processing approaches, but with the balloon inflationscalar values having variable values in a range from minimal or noeffective inflation to fully inflated.

Referring now to FIGS. 1-1 and 2, embodiments of articulation system 10will move the distal end 24 of catheter 12 toward a desired positionand/or orientation in a workspace relative to a base portion 21, withthe base portion often being adjacent to and proximal of actuatedportion 20. Note that such articulation may be relatively (or evencompletely) independent of any bending of catheter body 12 proximal ofbase portion 21. The location and orientation of proximal base 21(relative to handle 14 or to another convenient fixed or movablereference frame) may be identified, for example, by including knowncatheter position and/or orientation identification systems in system10, by including radiopaque or other high-contrast markers andassociated imaging and position and/or orientation identifying imageprocessing software in system 10, by including a flexible body statesensor system along the proximal portion of catheter body 12, byforegoing any flexible length of catheter body 12 between proximalhandle 14 and actuated portion 20, or the like. A variety of differentdegrees of freedom may be provided by actuated portion 20. Exemplaryembodiments of articulation system 10 may allow, for example, distal end24 to be moved with 2 degrees of freedom, 3 degrees of freedom, 4degrees of freedom, 5 degrees of freedom, or 6 degrees of freedomrelative to base portion 21. The number of kinematic degrees of freedomof articulated portion 20 may be much higher in some embodiments,particularly when a number of different alternative subsets of theballoon array could potentially be in different inflation states to givethe same resulting catheter tip and/or tool position and orientation.

Note that the elongate catheter body 12 along and beyond actuatedportion 20 may (and often should) remain flexible before, during, andafter articulation, so as to avoid inadvertently applying lateral and/oraxial forces to surrounding tissues that are beyond a safe threshold.Nonetheless, embodiments of the systems described herein may locally andcontrollably increase a stiffness of one or more axial portions ofcatheter body 12, along actuated portion 20, proximal of actuatedportion 20, and/or distal of actuated portion 20. Such selectivestiffening of the catheter body may be implemented with or withoutactive articulation capabilities, may extend along one or more axialportion of catheter body 12, and may alter which portions are stiffenedand which are more flexible in response to commands from the user,sensor input (optionally indicating axial movement of the catheter), orthe like.

As shown in FIG. 2, actuated portion 20 may comprise an axial series of2 or more (and preferably at least 3) actuatable sub-portions orsegments 20′, 20″, 20′″, with the segments optionally being adjacent toeach other, or alternatively separated by relatively short (less than 10diameters) and/or relatively stiff intermediate portions of catheter 12.Each sub-portion or segment may have an associated actuation array, withthe arrays working together to provide the desired overall cathetershape and degrees of freedom to the tip or tool. At least 2 of thesub-portions may employ similar articulation components (such as similarballoon arrays, similar structural backbone portions, similar valvesystems, and/or similar software). Commonality may include the use ofcorresponding actuation balloon arrays, but optionally with thecharacteristics of the individual actuation balloons of the differentarrays and the spacing between the locations of the arrays varying forany distal tapering of the catheter body. There may be advantages to theuse of differentiated articulation components, for example, withproximal and distal sub portions, 20′, 20′″ having similar structuresthat are configured to allow selective lateral bending with at least twodegrees of freedom, and intermediate portion 20″ being configured toallow variable axial elongation. In many embodiments, however, at leasttwo (and preferably all) segments are substantially continuous and sharecommon components and geometries, with the different segments havingseparate fluid channels and being separately articulatable but eachoptionally providing similar movement capabilities.

For those elongate flexible articulated structures described herein thatinclude a plurality of axial segments, the systems will often determineand implement each commanded articulation of a particular segment as asingle consistent articulation toward a desired segment shape state thatis distributed along that segment. In some exemplary embodiments, thenominal or resting segment shape state may be constrained to a 3 DOFspace (such as by continuous combinations of two transverse lateralbending orientations and an axial (elongation) orientation in an X-Y-Zwork space). In some of the exemplary embodiments described herein(including at least some of the helical extension/contractionembodiments), lateral bends along a segment may be at leastapproximately planar when the segment is in or near a design axiallength configuration (such as at or near the middle of the axial or Zrange of motion), but may exhibit a slight but increasing off-planetwisting curvature as the segment moves away from that designconfiguration (such as near the proximal and/or distal ends of the axialrange of motion). The off-plane bending may be repeatably accounted forkinematically by determining the changes in lateral orientation ofeccentric balloons resulting from winding and unwinding of helicalstructures supporting those balloons when the helical structuresincrease and decrease in axial length. For example, a segment may becommanded (as part of an overall desired pose or movement) to bend in a−Y orientation with a 20 degree bend angle. If the bend is to occur at adesign axial length (such as at the middle of the axial range ofmotion), and assuming balloons (or opposed balloon pairs) at 4 axialbend locations can be used to provide the commanded bend, the balloons(or balloon pairs) may each be inflated or deflated to bend the segmentby about 5 degrees (thereby providing a total bend of 5*4 or 20 degrees)in the −Y orientation. If the same bend is to be combined with axiallengthening of the segment to the end of its axial range of motion, theprocessor may determine that the segment may would exhibit some twist(say 2 degrees) so that there would be a slight +X component to thecommanded bend, so that the processor may compensate for the twist bycommanding a corresponding −X bend component, or by otherwisecompensating in the command for another segment of the flexible body.

Referring to FIGS. 3 and 5, catheter body 12 of system 10 includes anactuation array structure 32 mounted to a structural skeleton (here inthe form of a helical coil 34). Exemplary balloon array 32 includesfluid expandable structures or balloons 36 distributed at balloonlocations along a flexible substrate 38 so as to define an M×N array, inwhich M is an integer number of balloons distributed about acircumference 50 of catheter 12 at a given location along axis 30, and Nrepresents an integer number of axial locations along catheter 12 havingactuation balloons. Circumferential and axial spacing of the arrayelement locations will generally be known, and will preferably beregular. This first exemplary actuation array includes a 4×4 array for atotal of 16 balloons; alternative arrays may be from 1×2 arrays for atotal of 2 balloons to 8×200 arrays for a total of 1600 balloons (orbeyond), more typically having from 3×3 to 6×20 arrays. While balloonarrays of 1×N may be provided (particularly on systems that rely onrotation of the catheter body to orient a bend), M will more typicallybe 2 or more, more often being from 3 to 8, and preferably being 3 or 4.Similarly, while balloon arrays of M×1 may be provided to allowimposition of a single bend increment at a particular location in any ofa number of different desired lateral orientations, array 32 will moretypically have an N of from 2 to 200, often being from 3 to 20 or 3 to100. In contraction/expansion embodiments described below, multiplearrays may be provided with similar M×N arrays mounted in opposition.Not all array locations need have inflatable balloons, and the balloonsmay be arranged in more complex arrangements, such as with alternatingcircumferential numbers of balloons along the axis, or with varying oralternating separation between balloons along the axial length of thearray.

The balloons of a particular segment or that are mounted to a commonsubstrate may be described as forming an array, with the actuationballoon array structure optionally being used as a sub-array in amulti-segment or opposed articulation system. The combined sub-arraystogether may form an array of the overall device, which may also bedescribed simply as an array or optionally an overall or combined array.Exemplary balloon arrays along a segment or sub-portion of articulatedportion 20 include 1×8, 1×12, and 1×16 arrays for bending in a singledirection (optionally with 2, 3, 4, or even all of the balloons of thesegment in fluid communication with a single common inflation lumen soas to be inflated together) and 4×4, 4×8, and 4×12 arrays for X-Ybending (with axially aligned groups of 2-12 balloons coupled with 4 ormore common lumens for articulation in the +X, −X, +Y, and −Yorientations). Exemplary arrays for each segment having the opposedextension/retraction continuous articulation structures described hereinmay be in the form of a 3×2N, 3×3N, 4×2N, or 4×3N balloons arrays, forexample, 3×2, 3×4, 3×6, 3×8, 3×10, 3×12, 3×14, and 3×16 arrays with 6 to48 balloons, with the 3 lateral balloon orientations separated by 120degrees about the catheter axis. Extension balloons will often beaxially interspersed with contraction balloons along each lateralorientation, with separate 3×N arrays being combined together in a 3×2Nextension/contraction array for the segment, while two extensionballoons may be positioned axially between each contraction balloon for3×3N arrangements. The contraction balloons may align axially and/or bein plane with the extension balloons they oppose, though it may beadvantageous in some embodiments to arrange opposed balloons offset froma planer arrangement, so that (for example) two balloons of one typebalance one balloon of the other, or vice versa. The extension balloonsalong each orientation of the segment may share a common inflation fluidsupply lumen while the contraction balloons of the segment for eachorientation similarly share a common lumen (using 6 fluid supply lumensper segment for both 3×2N and 3×3N arrays). An extension/contractioncatheter may have from 1 to 8 such segments along the articulatedportion, more typically from 1 to 5 segments, and preferably being 2 to4 segments. Other medical and non-medical elongate flexible articulatedstructures may have similar or more complex balloon articulation arrays.

As can be seen in FIGS. 3, 4A, 4B, and 4C, the skeleton will often(though not always) include an axial series of loops 42. When the loopsare included in a helical coil 34, the coil may optionally be biased soas to urge adjacent loops 42 of the coil 34 toward each other. Suchaxially compressive biasing may help urge fluid out and deflate theballoons, and may by applied by other structures (inner and/or outersheath(s), pull wires, etc.) with or without helical compression. Axialengagement between adjacent loops (directly, or with balloon walls orother material of the array between loops) can also allow compressiveaxial forces to be transmitted relatively rigidly when the balloons arenot inflated. When a particular balloon is fully inflated, axialcompression may be transmitted between adjacent loops by the fullyinflated balloon wall material and by the fluid within the balloons.Where the balloon walls are non-compliant, the inflated balloons maytransfer these forces relatively rigidly, though with some flexing ofthe balloon wall material adjacent the balloon/skeleton interface. Rigidor semi-rigid interface structures which distribute axial loads across abroader balloon interface region may limit such flexing. Axial tensionforces (including those associated with axial bending) may be resistedby the biasing of the skeleton (and/or by other axial compressivestructures). Alternative looped skeleton structures may be formed, forexample, by cutting hypotube with an axial series of lateral incisionsacross a portion of the cross-section from one or more lateralorientations, braided metal or polymer elements, or the like. Non-loopedskeletons may be formed using a number of alternative known rigid orflexible robotic linkage architectures, including with structures basedon known soft robot structures. Suitable materials for coil 34 or otherskeleton structures may comprise metals such as stainless steel, springsteel, superelastic or shape-memory alloys such as Nitinol™ alloys,polymers, fiber-reinforced polymers, high-density or ultrahigh-densitypolymers, or the like.

When loops are included in the skeleton, actuation array 32 can bemounted to the skeleton with at least some of the balloons 36 positionedbetween two adjacent associated loops 42, such as between the loops ofcoil 34. Referring now to FIG. 4C, an exemplary deflated balloon 36 i islocated between a proximally adjacent loop 42 i and a distally adjacentloop 42 ii, with a first surface region of the balloon engaging adistally oriented surface of proximal loop 34 i, and a second surfaceregion of the balloon engaging a proximally oriented surface of distalloop 42 ii. The walls of deflated balloon 36 i have some thickness, andthe proximal and distal surfaces of adjacent loops 42 i and 42 iimaintain a non-zero axial deflated offset 41 between the loops. Axialcompression forces can be transferred from the loops through the solidballoon walls. Alternative skeletal structures may allow the loops toengage directly against each other so as to have a deflated offset ofzero and directly transmit axial compressive force, for example byincluding balloon receptacles or one or more axial protrusions extendingfrom one or both loops circumferentially or radially beyond the balloonand any adjacent substrate structure. Regardless, full inflation of theballoon will typically increase the separation between the adjacentloops to a larger full inflation offset 41′. The simplified lateralcross-sections of FIGS. 4B, 4C, and 4D schematically show a directinterface engagement between a uniform thickness thin-walled balloon anda round helical coil loop. Such an interface may result in relativelylimited area of the balloon wall engaging the coil and associateddeformation under axial loading. Alternative balloon-engaging surfaceshapes along the coils (often including locally increased convex radii,locally flattened surfaces, and/or local concave balloon receptacles)and/or along the coil-engaging surfaces of the balloon (such as bylocally thickening the balloon wall to spread the engagement area),and/or providing load-spreading bodies between the balloons and thecoils may add axial stiffness. A variety of other modifications to theballoons and balloon/coil interfaces may also be beneficial, includingadhesive bonding of the balloons to the adjacent coils, including foldsor material so as to inhibit balloon migration, and the like.

Inflation of a balloon can alter the geometry along catheter body 12,for example, by increasing separation between loops of a helical coil soas to bend axis 30 of catheter 12. As can be understood with referenceto FIGS. 1B, 1C and 4-4C, selectively inflating an eccentric subset ofthe balloons can variably alter lateral deflection of the catheter axis.As can be understood with reference to FIGS. 1A, 4, and 4D, inflation ofall (or an axisymmetric subset) of the balloons may increase an axiallength of the catheter structure. Inflating subsets of the balloons thathave a combination of differing lateral orientations and axial positionscan provide a broad range of potential locations and orientations of thecatheter distal tip 26, and/or of one or more other locations along thecatheter body (such as where a tool is mounted).

Some or all of the material of substrate 38 included in actuation array32 will often be relatively inelastic. It may, however, be desirable toallow the skeleton and overall catheter to flex and/or elongate axiallywith inflation of the balloons or under environmental forces. Hence,array 32 may have cutouts 56 so as to allow the balloon array to moveaxially with the skeleton during bending and elongation. The arraystructure could alternatively (or in addition) be configured for sucharticulation by having a serpentine configuration or a helical coiledconfiguration. Balloons 36 of array 32 may include non-compliant balloonwall materials, with the balloon wall materials optionally being formedintegrally from material of the substrate or separately. Note thatelastic layers or other structures may be included in the substrate foruse in valves and the like, and that some alternative balloons mayinclude elastic and/or semi-compliant materials.

Referring to FIGS. 3, 4A, and 5, substrate 38 of array 32 is laterallyflexible so that the array can be rolled or otherwise assume acylindrical configuration when in use. The cylindrical array may becoaxially mounted to (such as being inserted into or radially outwardlysurrounding) the helical coil 34 or other structural backbone of thecatheter. The cylindrical configuration of the array will generally havea diameter that is equal to or less than an outer diameter of thecatheter. The opposed lateral edges of substrate 38 may be separated bya gap as shown, may contact each other, or may overlap. Contacting oroverlapping edges may be affixed together (optionally so as to help sealthe catheter against radial fluid flow) or may accommodate relativemotion (so as to facilitate axial flexing). In some embodiments, lateralrolling or flexing of the substrate to form the cylindricalconfiguration may be uniform (so as to provide a continuous lateralcurve along the major surfaces), while in other embodiments intermittentaxial bend regions of the substrate may be separated by axially elongaterelatively flat regions of the substrate so that a cylindrical shape isapproximated by a prism-like arrangement (optionally so as to limitbending of the substrate along balloons, valves, or other arraycomponents).

It will often (though not always) be advantageous to form and/orassemble one or more components of the array structure in a flat,substantially planar configuration (and optionally in a linearconfiguration as described below). This may facilitate, for example,partial or final formation of balloons 36 on substrate 38, oralternatively, attachment of pre-formed balloons to the substrate. Theflat configuration of the substrate may also facilitate the use of knownextrusion or microfluidic channel fabrication techniques to providefluid communication channels 52 so as to selectively couple the balloonswith a fluid inflation fluid source or reservoir 54, and the like. Stillfurther advantages of the flat configuration of the substrate mayinclude the use of electrical circuit printing techniques to fabricateelectrical traces and other circuit components, automated 3-D printingtechniques (including additive and/or removal techniques) for formingvalves, balloons, channels, or other fluid components that will besupported by substrate 38, and the like. When the substrate is in arolled, tubular, or flat planar configuration, the substrate willtypically have a first major surface 62 adjacent balloons 36, and asecond major surface 64 opposite the first major surface (with firstmajor surface 62 optionally being a radially inner or outer surface andsecond major surface 64 being a radially outer or inner surface,respectively, in the cylindrical configuration). To facilitate flexingsubstrate 38 and array 32 into the rolled configuration, relief cuts orchannels may be formed extending into the substrate from the firstand/or second major surfaces, or living hinge regions may otherwise beprovided between relatively more rigid portions of the substrate. Tofurther avoid deformation of the substrate adjacent any valves or othersensitive structures, local stiffening reinforcement material may beadded, and/or relief cuts or apertures may be formed partiallysurrounding the valves. In some embodiments, at least a portion of thearray components may be formed or assembled with the substrate at leastpartially in a cylindrical configuration, such as by bonding layers ofthe substrate together while the substrate is at least locally curved,forming at least one layer of the substrate as a tube, selectivelyforming cuts in the substrate (optionally with a femtosecond,picosecond, or other laser) to form fluid, circuit, or other componentsor allow for axial flexing and elongation (analogous to cutting a stentto allow for axial flexing and radial expansion) and/or to form at leastsome of the channels, and bonding the layers together after cutting.

As can be understood with reference to FIGS. 5-5C, substrate 38 of array32 may include one or more layers 70, 72, 74 . . . of flexible substratematerial. The substrate layers may comprise known flexible and/or rigidmicrofluidic substrate materials, such as polydimethylsiloxane (PDMS),polyimide (PI), polyethylene (PE) and other polyolefins, polystyrene(PS), polyethylene terephthalate (PET), polypropylene (PP),polycarbonate (PC), nanocomposite polymer materials, glass, silicon,cyclic olefin copolymer (COC), polymethyl methacrylate (PMMA),polyetheretherketone (PEEK), polyester, polyurethane (PU), and/or thelike. These and still further known materials may be included in othercomponents of actuation array 32, including known polymers for use inballoons (which will often include PET, PI, PE, polyether block amide(PEBA) polymers such as PEBAX™ polymers, nylons, urethanes, polyvinylchloride (PVC), thermoplastics, and/or the like for non-compliantballoons; or silicone, polyurethane, semi-elastic nylons or otherpolymers, latex, and/or the like for compliant or semi-compliantballoons). Additional polymers than may be included in the substrateassembly may include valve actuation elements (optionally includingshape memory alloy structures or foils; phase-change actuator materialssuch as paraffin or other wax, electrical field sensitive hydrogels,bimetallic actuators, piezoelectric structures, dielectric elastomeractuator (DEA) materials, or the like). Hence, while some embodimentsmay employ homogenous materials for actuation array 32, many arrays andsubstrate may instead be heterogeneous.

Fortunately, techniques for forming and assembling the components foractuation array 32 may be derived from a number of recent (andrelatively widely-reported) technologies. Suitable techniques forfabricating channels in substrate layer materials may include lasermicromachining (optionally using femtosecond or picosecond lasers),photolithography techniques such as dry resist technologies, embossing(including hot roller embossing), casting or molding, xerographictechnologies, microthermoforming, stereolithography, 3-D printing,and/or the like. Suitable 3-D printing technologies that may be used toform circuitry, valves, sensors, and the like may includestereolithography, digital light processing, laser sintering or melting,fused deposition modeling, inkjet printing, selective depositionlamination, electron beam melting, or the like. Assembly of thecomponents of actuation array 32 may make use of laser, thermal, and/oradhesive bonding between layers and other components, though laser,ultrasound, or other welding techniques; microfasteners, or the like mayalso be used. Electrical element fabrication of conductive traces,actuation, signal processor, and/or sensor components carried bysubstrate 38 may, for example, use ink-jet or photolithographytechniques, 3-D printing, chemical vapor deposition (CVD) and/or morespecific variants such as initiated chemical vapor deposition (iCVD),robotic microassembly techniques, or the like, with the electricaltraces and other components often comprising inks and other materialscontaining metals (such as silver, copper, or gold) carbon, or otherconductors. Many suitable fabrication and assembly techniques have beendeveloped during development of microfluidic lab-on-a-chip orlab-on-a-foil applications. Techniques for fabricating medical balloonsare well developed, and may optionally be modified to take advantage ofknown high-volume production techniques (optionally including thosedeveloped for fabricating bubble wrap, for corrugating extruded tubing,and the like). Note that while some embodiments of the actuation arraystructures described herein may employ fluid channels sufficiently smallfor accurately handling of picoliter or nanoliter fluid quantities,other embodiments will include channels and balloons or otherfluid-expandable bodies that utilize much larger flows so as to providedesirable actuation response times. Balloons having at least partiallyflexible balloon walls may provide particular advantages for the systemsdescribed herein, but alternative rigid fluid expandable bodies such asthose employing pistons or other positive displacement expansionstructures may also find use in some embodiments.

The structures of balloons 36 as included in actuation array 32 may beformed of material integral with other components of the array, or maybe formed separately and attached to the array. For example, as shown inFIGS. 5B and 5C, balloons 36 may be formed from or attached to a firstsheet 74 of substrate material that can be bonded or otherwise affixedto another substrate layer 72 or layers. The material of the balloonlayer 74 may optionally cover portions of the channels directly, or maybe aligned with apertures 78 that open through an intermediate substratelayer surface between the channels and the balloons. Apertures 78 mayallow fluid communication between each balloon and at least oneassociated channel 52. Alternative methods for fabricating individualballoons are well known, and the formed balloons may be affixed to thesubstrate 38 by adhesive bonding. Balloon shapes may comprise relativelysimple cylinders or may be somewhat tailored to taper to follow anexpanded offset between loops of a coil, to curve with the cylindricalsubstrate and/or to engage interface surfaces of the skeleton over abroader surface area and thereby distribute actuation and environmentalloads. Effective diameters of the balloons in the array may range fromabout 0.003 mm to as much as about 2 cm (or more), more typically beingin a range from about 0.3 mm to about 2 mm or 5 mm, with the balloonlengths often being from about 2 to about 15 times the diameter. Typicalballoon wall thicknesses may range from about 0.0002 mm to about 0.004mm (with some balloon wall thicknesses being between 0.0002 mm and 0.020mm), and full inflation pressures in the balloons may be from about 0.2to about 40 atm, more typically being in a range from about 0.4 to about30 atm, and in some embodiments being in a range from about 10 to about30 atm, with high-pressure embodiments operating at pressures in a rangeas high as 20-45 atm and optionally having burst pressures of over 50atm.

Referring now to FIG. 5, balloons 36 will generally be inflated using afluid supply system that includes a fluid source 54 (shown here as apressurized single-use cartridge) and one or more valves 90. At leastsome of the valves 90 may be incorporated into the balloon arraysubstrate, with the valves optionally being actuated using circuitryprinted on one or more layers of substrate 38. With or withoutsubstrate-mounted valves that can be used within a patient body, atleast some of the valves may be mounted to housing 14, or otherwisecoupled to the proximal end of catheter 12. Valves 90 will preferably becoupled to channels 52 so as to allow the fluid system to selectivelyinflate any of a plurality of alternative individual balloons or subsetsof balloons 36 included in actuation array 32, under the direction of aprocessor 60. Hence, processor 60 will often be coupled to valves 90 viaconductors, the conductors here optionally including flex circuit traceson substrate 38.

Referring still to FIG. 5, fluid source 54 may optionally comprise aseparate fluid reservoir and a pump for pressurizing fluid from thereservoir, but will often include a simple tank or cartridge containinga pressurized fluid, the fluid optionally being a gas or a gas-liquidmixture. The cartridge will often maintain the fluid at a supplypressure at or above a full inflation pressure range of balloons 36,with the cartridge optionally being gently heated by a resistive heateror the like (not shown) in housing 14 so as to maintain the supplypressure within a desired range in the cartridge during use. Supplypressures will typically exceed balloon inflation pressures sufficientlyto provide balloon inflation times within a target threshold given thepressure loss through channels 52 and valves 90, with typical supplypressures being between 10 and 210 atm, and more typically being between20 and 60 atm. Suitable fluids may include known medical pressurizedgases such as carbon dioxide, nitrogen, oxygen, nitrous oxide, air,known industrial and cryogenic gasses such as helium and/or other inertor noble gasses, refrigerant gases including fluorocarbons, and thelike. Note that the pressurized fluid in the canister can be directedvia channels 52 into balloons 36 for inflation, or the fluid from thecanister (often at least partially a gas) may alternatively be used topressurize a fluid reservoir (often containing or comprising a benignbiocompatible liquid such as water or saline) so that the ballooninflation fluid is different than that contained in the cartridge. Wherea pressurized liquid or gas/liquid mixture flows distally along thecatheter body, enthalpy of vaporization of the liquid in or adjacent tochannels 52, balloons 36, or other tissue treatment tools carried on thecatheter body (such as a tissue dilation balloon, cryogenic treatmentsurface, or tissue electrode) may be used to therapeutically cooltissue. In other embodiments, despite the use of fluids which are usedas refrigerants within the body, no therapeutic cooling may be provided.The cartridge may optionally be refillable, but will often instead havea frangible seal so as to inhibit or limit re-use.

As the individual balloons may have inflated volumes that are quitesmall, cartridges that are suitable for including in a hand-held housingcan allow more than a hundred, optionally being more than a thousand,and in many cases more than ten thousand or even a hundred thousandindividual balloon inflations, despite the cartridge containing lessthan 10 ounces of fluid, often less than 5 ounces, in most cases lessthan 3 ounces, and ideally less than 1 ounce. Note also that a number ofalternative fluid sources may be used instead of or with a cartridge,including one or more positive displacement pumps (optionally such assimple syringe pumps), a peristaltic or rotary pump, any of a variety ofmicrofluidic pressure sources (such as wax or other phase-change devicesactuated by electrical or light energy and/or integrated into substrate38), or the like. Some embodiments may employ a series of dedicatedsyringe or other positive displacement pumps coupled with at least someof the balloons by channels of the substrate, and/or by flexible tubing.

Referring still to FIG. 5, processor 60 can facilitate inflation of anappropriate subset of balloons 36 of actuation array 32 so as to producea desired articulation. Such processor-derived articulation cansignificantly enhance effective operative coupling of the input 18 tothe actuated portion 20 of catheter body 12, making it much easier forthe user to generate a desired movement in a desired direction or toassume a desired shape. Suitable correlations between input commands andoutput movements have been well developed for teleoperated systems withrigid driven linkages. For the elongate flexible catheters and otherbodies used in the systems described herein, it will often beadvantageous for the processor to select a subset of balloons forinflation based on a movement command entered into a user interface 66(and particularly input 18 of user interface 66), and on a spatialrelationship between actuated portion 20 of catheter 12 and one or morecomponent of the user interface. A number of differing correlations maybe helpful, including orientational correlation, displacementcorrelation, and the like. Along with an input, user interface 66 mayinclude a display showing actuated portion 20 of catheter body 12, andsensor 63 may provide signals to processor 60 regarding the orientationand/or location of proximal base 21. Where the relationship between theinput, display, and sensor are known (such as when they are all mountedto proximal housing 14 or some other common base), these signals mayallow derivation of a transformation between a user interface coordinatesystem and a base coordinate system of actuated portion 20. Alternativesystems may sense or otherwise identify the relationships between thesensor coordinate system, the display coordinate system, and/or theinput coordinate system so that movements of the input result incatheter movement, as shown in the display. Where the sensor comprisesan image processor coupled to a remote imaging system (such as afluoroscopy, MM, or ultrasound system), high-contrast marker systems canbe included in proximal base 21 to facilitate unambiguous determinationof the base position and orientation. A battery or other power source(such as a fuel cell or the like) may be included in housing 14 andcoupled to processor 60, with the housing and catheter optionally beingused as a handheld unit free of any mechanical tether during at least aportion of the procedure. Nonetheless, it should be noted that processor60 and/or sensor 63 may be wirelessly coupled or even tethered together(and/or to other components such as a separate display of user interface66, an external power supply or fluid source, or the like).

Regarding processor 60, sensor 63, user interface 66, and the other dataprocessing components of system 10, it should be understood that thespecific data processing architectures described herein are merelyexamples, and that a variety of alternatives, adaptations, andembodiments may be employed. The processor, sensor, and user interfacewill, taken together, typically include both data processing hardwareand software, with the hardware including an input (such as a joystickor the like that is movable relative to housing 14 or some other inputbase in at least 2 dimensions), an output (such as a medical imagedisplay screen), an image-acquisition device or other sensor, and one ormore processor. These components are included in a processor systemcapable of performing the image processing, rigid-body transformations,kinematic analysis, and matrix processing functionality describedherein, along with the appropriate connectors, conductors, wirelesstelemetry, and the like. The processing capabilities may be centralizedin a single processor board, or may be distributed among the variouscomponents so that smaller volumes of higher-level data can betransmitted. The processor(s) will often include one or more memory orstorage media, and the functionality used to perform the methodsdescribed herein will often include software or firmware embodiedtherein. The software will typically comprise machine-readableprogramming code or instructions embodied in non-volatile media, and maybe arranged in a wide variety of alternative code architectures, varyingfrom a single monolithic code running on a single processor to a largenumber of specialized subroutines being run in parallel on a number ofseparate processor sub-units.

Referring now to FIG. 5A, an alternative actuation array and fluidsupply system are shown schematically. As in the above embodiment,balloons 36 are affixed along a major surface of substrate 38,optionally prior to rolling the substrate and mounting of the actuationarray to the skeleton of the catheter body. In this embodiment, eachballoon has an associated dedicated channel 52 of substrate 38, and alsoan associated valve 90. Processor 60 is coupled with valves 90, and byactuating a desired subset of the valves the associated subset ofballoons can be inflated or deflated. In some embodiments, each valvecan be associated with more than one balloon 36, so that (for example),opening of a single valve might inflate a plurality (optionally 2, 3, 4,8, 12, or some other desired number) of balloons, such as laterallyopposed balloons so as to elongate the distal portion of the catheter.In these or other embodiments, a plurality of balloons (2, 3, 4, 5, 8,12, or another desired number) on one lateral side of the catheter couldbe in fluid communication with a single associated valve 90 via a commonchannel or multiple channels so that opening of the valve inflates theballoons and causes a multi-balloon and multi-increment bend in the axisof the catheter. Still further variations are possible. For example, insome embodiments, channels 52 may be formed at least in-part by flexibletubes affixed within an open or closed channel of substrate 38, or gluedalong a surface of the substrate. The tubes may comprise polymers (suchas polyimide, PET, nylon, or the like), fused silica, metal, or othermaterials, and suitable tubing materials may be commercially availablefrom Polymicro Technologies of Arizona, or from a variety of alternativesuppliers. The channels coupled to the proximal end of the actuatablebody may be assembled using stacked fluidic plates, with valves coupledto some or all of the plates. Suitable electrically actuated microvaluesare commercially available from a number of suppliers. Optionalembodiments of fluid supply systems for all balloon arrays describedherein may have all values mounted to housing 14 or some other structurecoupled to and/or proximal of) the proximal end of the elongate flexiblebody. Advantageously, accurately formed channels 52 (having sufficientlytight tolerance channel widths, depths, lengths, and/or bends or otherfeatures) may be fabricated using microfluidic techniques, and may beassembled with the substrate structure, so as to meter flow of theinflation fluid into and out of the balloons of all of the actuationarrays described herein.

Referring now to FIGS. 5B and 5C, two alternative substrate layerstructures and valves are shown schematically. A variety of knownlab-on-a-chip and lab-on-a-foil production techniques can be used toassemble and seal the substrate layers, with many embodiments employingthermal fusion bonding, solvent bonding, welding (and particularlyultrasound welding), UV-curable adhesives, contact adhesives,nano-adhesives (including doubly cross-linked nano-adhesive or DCNA),epoxy-containing polymers (including polyglycidyl methacrylate), plasmaor other surface modifications, and/or the like between layers. For highfluid pressure systems, third generation nano-adhesive techniques suchas CVD deposition of less than 400 nanometer layers of DCNA materialsmay facilitate the use of high-strength polymer materials such as PET.Channels of such high-pressure systems may optionally be defined atleast in part by PET and/or fused silica tubing (which may be supportedby a substrate along some or all of the channel, and/or may be bundledtogether with other fused silica tubing along some or all of its lengthideally in an organized array with tubing locations corresponding to theballoon locations within the balloon array, analogous to theorganization of a coherent fiber optic bundle), or the like. As shown inthe embodiment of FIG. 5B, any valves (such as valve 90 a) mounted tothe substrate of the balloon array may be electrically actuated usingconductive traces 73 deposited on a surface of a substrate layer (suchas layer 70) prior to bonding, with an overlying layer (such as layer72) sealing the traces in the interior of the substrate. A valve member91 of valve 90 may move when a potential is applied to an actuationmaterial 93 using the traces, with that material optionally comprising ashape-memory alloy, piezoelectric, an electrically actuated polymer, orthe like. Still further alternative actuation materials may includephase change materials such as wax or the like, with the phase changebeing induced by electrical energy or optical energy (such as laserlight transmitted via an optical fiber or printed pathway between layersof the substrate). In some embodiments, the actuation material and valvemember may be formed using 3-D printing techniques. Multiplex circuitrymay be included in, deposited on a layer of, or affixed to substrate 38so that the number of electrical traces extending proximally alongcatheter body 12 may be less than the number of valves that can beactuated by those valves. The valves may take any of a wide variety offorms, and may employ (or be derived from) known valve structures suchas known electrostatically-actuated elastomeric microfluidic valves,microfluidic polymer piston or free-floating gate valves, layeredmodular polymeric microvalves, dielectric elastomer actuator valves,shape memory alloy microvalves, hydrogel microactuator valves,integrated high-pressure fluid manipulation valves employing paraffin,and the like. Along with electrically actuated microvalves, suitablevalves may be optically actuated, fluid actuated, or the like.

Regarding FIG. 5C, an alternative fluid-actuated valve includes anelastomeric layer 77 between a balloon inflation channel 52 and atransverse actuation channel 75. As is often done in commercialmicrofluidic structures, fluid pressure in the actuation channel canpush the elastomeric layer 52 into channel 52 to sufficiently seal theballoon inflation channel 52 to inhibit flow, here to inhibit into orout of the balloon. The actuation fluid flow may be from the sameoriginal fluid source as the balloon inflation fluid or a differentsource, and may be at a different pressure. Still further transverseactuation fluid channels and valves may be provided so as to allowcontrol over a greater number of balloons than there are channels in atleast the proximal portion of the catheter.

It should be understood that many of the valves shown herein areschematic, and that additional or more complex valves and channelsystems may be included to control inflation and deflation of theballoons. One or more valves in the system may comprise gate valves(optionally normally closed, normally open or stable), so as to turninflation fluid flow from the fluid source to at least one balloon on oroff. Deflation may optionally be controlled by a separate gate valvebetween each balloon (or groups of balloons) and one or more deflationport of substrate 38 (the fluid from the balloon optionally exiting fromthe substrate to flow proximally between radially inner and outer sealedlayers of the catheter) or housing 14. Alternative 2-way valves mayallow i) communication between either the fluid source and the balloon(with flow from the balloon being blocked), or ii) between the balloonand the deflation outflow (with the flow from the fluid source beingblocked). Still further alternatives may be employed, including a 3 wayvalve having both of the above modes and iii) a sealed balloon mode inwhich the balloon is sealed from communication with the fluid source andfrom the deflation outflow (with flow from the source also beingclosed).

Referring now to FIG. 6A, an alternative embodiment of catheter body 12includes a substrate 38 with balloons 36 extending radially inwardlyfrom the substrate. Lateral edges of substrate 36 may be affixedtogether at least intermittently (particularly axially along balloons36) so as to limit radial expansion of the substrate (and therebyballoons 36 from migrating radially out from between the loops of theskeleton). Referring now to FIG. 6B, yet another alternative embodimentof catheter body 12 has both an inner helical coil 92 (disposed radiallyinward of substrate 38), and an outer helical coil 34 (disposed radiallyoutward of the substrate). The inner coil may help keep the balloons andsubstrate from migrating inward from the desired position, with ourwithout affixing the edges of the substrate together.

Referring now to FIGS. 6C-6H, optional catheter structures employ analternative balloon array structure having one or more elongate balloons96, 204 that each extend axially, with the balloons here being formed ina layered substrate 208 so that the balloons together define a balloonarray 206 that can frictionally engage or latch against coils to helpinhibit lateral bending of a catheter body. When deflated, the loops 42,100, 202 of the helical coils can move away from (or if separated,toward) each other, allowing the catheter body to flex (and straighten).In contrast, fluid expansion of balloons 204 causes each axial balloonto radially engage a plurality of coils 202, inhibiting movement of thecoils toward or away from each other so as to add axial stiffness to thecatheter body. Interestingly, this can make it more difficult to bend astraight portion of the catheter, and/or can make it more difficult fora bent portion of the catheter to straighten (or otherwise alter itsaxial configuration). As described above, substrate 38, 208 may bedisposed between inner and outer coils so that the axially orientedballoons radially engage either (or both); or the substrate may bedisposed radially outward of the coil to be engaged with the edges ofthe substrate affixed together so as to limit radial displacement of theballoons and promote firm radial engagement between the expanded balloonand the coil. Still further alternatives are available, including theuse of semi-rigid or other radial support materials in the substrate,with or without edges affixed together. As can also be understood withreference to FIGS. 4C and 6A, bend-inducing balloons may be combinedwith bend-inhibiting balloons by including both types of balloons on asingle substrate (optionally on opposed sides) or on separatesubstrates. Advantageously, the substrate, balloon, and fluid supply andcontrol structures of these bend-change-inhibiting balloon arrays mayinclude the characteristics described above for the correspondingstructures of the balloon articulation systems. Note that the simplifiedschematic stiffening balloon array of FIG. 6D is merely representative(showing axial overlap of sets of three balloons, with the sets offsetto allow continuous stiffening throughout a segment). To facilitatebending of the segment when the balloons are not inflated, the substratemay have lateral cuts 56 (as shown in FIG. 5), the array may be arrangedin partially overlapping substrate areas with substrate/substratesliding between the balloons 96 (such as by using a helical substratearrangement as may be understood with reference to FIGS. 7G and 7I), orthe like.

Referring now to FIGS. 6E and 6H, an alternative local stiffening system200 includes a helical coil 202 defining an axis and one or more balloon204, with the balloon often being included in a balloon array structure206 having an array of balloons, a substrate 208, channels within oraffixed to the substrate, and the like. Substrate 208 is also used toform a circumferential band encircling the coil and some or all of theballoons and disposed radially outward of the coil 202, typically byaffixing the edges of the substrate together when rolled, forming thesubstrate using tube material, or the like. As the balloon iseffectively held radially between the coil and this band of substratematerial, expansion of the balloon can induce circumferential tension inthe band. The band can thus act as a radial hoop support, even if formedof a flexible material, so that the expanded balloon is maintained ifsufficient engagement with the adjacent loops of the coil to inhibitaxial sliding therebetween. Note that if the catheter or other elongatebody is axially bent prior to balloon expansion (as shown in FIG. 6H)the inflation of balloon 204 may be used to help inhibit changes to thatbent configuration. The inflated balloon may, however, be at leastsomewhat biased to assume a straight shape, so that there may beadvantages to limiting the axial length of each balloon to less than 3times the overall diameter of the catheter (optionally being less than 2times), though other embodiments may use longer stiffening balloons.

As can be understood with reference to FIGS. 6A-6E, axial movementinhibiting features or surfaces may be included on the stiffeningballoons or coils or both so as to limit any movement between theexpanded balloons and the loops they engage. As shown, the coil mayinclude one or more radially oriented protruding feature or edge.Alternatively (or in combination), the balloons may have protrudingfeatures or ribs, and/or one or both corresponding engagement surfacesmay comprise a high friction or stiction surface.

As shown in FIGS. 6F and 6G, in some embodiments of the stiffeningand/or articulation balloon array structures described herein, balloons210 may optionally be formed separately from the array substrate 212,optionally using known techniques for blowing non-compliant medicalballoons from tube material or the like. Such balloons may be affixed tosubstrate 212 at least in part by bonding the balloon between a first(optionally thicker) layer of the substrate 214 and a second (optionallythinner) substrate layer 216. Second layer 216 may primarily conform tothe shape of the first layer, balloons 210, and optionally anyseparately formed tubing used for channels of the fluid supply system,with the second layer optionally comprising a polymer such as athermoplastic that can shaped using heating and differential pressure.Second layer 216 may be more compliant than first layer 214, so that theballoon expands from substrate 212 primarily in the direction of secondlayer 216. Second layer 216 may optionally be more resilient than firstlayer 212, and/or may have a surface 218 that has a relatively highfriction or stiction. When used in a selective stiffening balloon arraystructure, a third layer of polymer having a low friction or stictionsurface 220 may also be included in the substrate array, with secondlayer being between the first and third layers. When balloon 210 is in adeflated configuration, high-stiction or friction surface 220 may berecessed below the third lay so that the adjacent loops of the coil arefree to move relative to each other despite any incidental contact withthe low friction surface of third layer 220. When balloon 210 isinflated, the high stiction or friction surface 218 of second layer 216is exposed so as to engage the loops of the coil, thereby inhibitingrelative movement of the coils (including changing of axial offsetsbetween the coils) and bending of the skeleton axis adjacent the engagedloops.

Referring now to FIGS. 6I, 6J, and 6L, yet another alternative arraystructure 102 includes apertures 104 through a substrate 106 around acircumferential portion (but not completely surrounding) at least someof balloons 36. The apertures 104 define tabs of substrate material 108,balloons 36, and adjacent channel portions 52 (seen in FIG. 6I) that canbe bent radially from the adjacent substrate material before or afterthe substrate has been rolled to the circumferential configuration(shown in FIG. 6J). This facilitates forming expandable balloon wallsfrom the layers of the substrate (optionally by locally decreasing athickness of one or both adjacent substrate layers along an interface,locally heating and inflating the heated substrate material within moldsto form balloon walls. As with other rolled substrate structures,lateral incisions 56 (shown in FIG. 5) and/or a helical rolled substrateconfiguration with sliding between any overlapping substrate regions mayhelp maintain flexibility of the assembly.

Referring to FIGS. 6K and 6L, details of the interface surfaces betweenthe balloons and the adjacent coils can be seen. Each axial bending orelongation balloon 36 will typically be disposed between a distallyoriented surface of a proximally adjacent loop 42 i, and a proximallyoriented surface of a distally adjacent loop 42 ii. Balloons 36 often(though not always) have convex surfaces when expanded. While helicalcoils can be formed of wires or polymers with flat or even concaveproximal and distal surfaces, many helical coils are formed from roundwires having convex distal and proximal surfaces. To limit axialdeflection associated with localized deflection of the inflated balloonwalls, it will often be beneficial to distribute axial loads transmittedbetween the skeleton and the balloon over a region of the balloonsurface that is larger than that provided by convex surface to convexsurface engagement. Hence, use of coil structures having concaveproximal and distal coil surfaces (at least adjacent balloons 36) willprovide greater inflated axial stiffness. As can be understood withreference to in FIG. 10, axial loads can be distributed from a helicalcoil having a flat or convex surface using an intermediate body ormaterial 112 between the adjacent proximal skeleton surface and balloon,and/or between the adjacent distal skeleton surface and a balloon. Theintermediate material may optionally be affixed to (or even integratedinto) the balloon wall adjacent the coil, or the coil adjacent theballoon, or may be a structure that is separate from both. Theintermediate body or material 112 may have cooperating axial engagementsurfaces 114 that press against each other (directly or through adeflated balloon wall) so as to transmit axial loads with limiteddeflection when the balloon is deflated.

Also shown in FIG. 6K is an outer barrier sheath 120 disposed radiallyover the coil 34 and actuation array 32 so as to contain inflation fluidreleased from the array. The sheath 120 may have a plurality of polymerlayers 122, 124 with a separation material 126 (such as a braid, wovencloth, or felt) between the layers. A vacuum may be applied to the spacebetween the polymer layers 122, 124 by a simple manual syringe pump orthe like, and the vacuum can be monitored to verify fluid sealing in thesystem. Alternative simpler barrier sheaths may comprise a singlepolymer layer. An inner barrier sheath may be provided with or withoutthe outer barrier sheath, and one or both barrier sheaths may beintegral with substrates of one or more actuation array(s). Sealinginner and outer barrier sheaths to each other (such as substrate 38 topolymer layer 124) distally of the actuatable portion may allow thefluid inflation fluid to be released or ported from the substrate(s) soas to flow proximally around the coil, balloons, etc. between thebarrier sheaths in any or all of the embodiments described herein. Avacuum drawn between inner and outer sheaths (for example, in the areasurrounding coil 34 and balloons 36) may be used to verify sealing aboutmuch or all of the fluid handling components, with the vacuum and vacuummonitoring system generally being simpler when the used inflation fluidis transmitted proximally within channels of the substrate.

Referring now to FIGS. 6K and 6L, axial coupling of corresponding axialsurfaces 114 of the skeleton when the balloon is deflated can beunderstood. In the embodiment of FIG. 6K, the axial surfaces of theskeleton are configured to transmit axial loads indirectly through thethrough deflated balloon wall. In the embodiment of FIG. 6L, as shown bythe deflated left-most balloon 36, the radially outward axial surfaces114 of the skeleton 130 are configured to engage each-other directly.Also seen in FIG. 6L are convex surface balloon receptacle surfaces 134that can limit axial deflection by distributing axial loads over acrossthe surface of the inflated balloons 36.

As noted above, helical structural skeletons can be biased to axiallycompress and help deflate balloons. Additional passive or activestructures axial compression structures can also help maintain thearticulatable structures in the commanded configuration, with or withoutsuch helical coil biasing. In FIG. 6K, the outer barrier sheath 120comprises an axially resilient compressive sheath. The sheath istensioned axially and applies a load 140 over some or all of the lengthof the actuated portion. During use, sheath 120 may be affixed to theskeleton distally of the actuated portion 20 and proximal of theactuated portion 20 (see FIG. 1-1). To enhance shelf life, the sheathmay be shipped in a less stressed configuration and then pulledproximally and affixed to the catheter body 12 proximal of actuatedportion 20 or proximal housing 14 prior to use (see FIG. 1-1). In FIG.6L, a plurality of active pull-wires may extend along at least a portionof the actuated portion 20 of catheter 12, with the pull wires beingdistributed circumferentially around the axis of the catheter. Motors orsprings may be used to actively pull the pull wires to help deflate theballoons and maintain the overall configuration or pose of the catheterdespite environmental forces. A variety of alternatives may be employed,including use of a single actively tensioned central pull wire, activelytensioning an inner or outer sheath, or the like.

Referring now to FIGS. 6M-6P, exemplary balloon geometry and fabricationtechniques can be understood. First addressing the simplified schematicof FIG. 6M, a portion of a balloon array structure 220 includes aballoon 222 and a substrate 224. Balloon 222 extends circumferentiallyaround an axis of the curved substrate (and of the associated skeleton,omitted for simplicity here) so as to define an arc angle α. As can beunderstood with reference to FIGS. 6N and 6P, balloon 222 may have afirst diameter 226, typically near a circumferential mid-portion of theballoon. The balloon diameter may taper to a smaller diameter 228 towardcircumferential ends of the balloon so as to promote balloon/coilinterface engagement throughout the arc angle, as can be understood withreference to FIG. 6P. Additionally, as balloon 222 extends radiallyoutward of substrate 224, the radial outer surface of the balloon maybenefit from having sufficient material length so that inflation of theballoon does not tend to locally flatten the substrate 224 along the arcangle α.

A tool and method to facilitate fabrication of a balloon having both avarying diameter and sufficient material along the outer surface,despite the balloon wall being formed while the substrate is in a flatconfiguration, can be understood with reference to FIG. 6O. In thisembodiment, a channel 228 has been formed in a first substrate layer230, optionally via laser micromachining, molding, or the like. Theballoon wall will primarily be defined by a second substrate layer 232,with the second layer being formed by using differential pressure tourge or blow the second layer against a tool 234. Note that while secondlayer 232 may be blown after the first and second layer are bondedtogether through channel 228, it may instead be easier to form theballoon wall prior to bonding the substrate layers. In preparation forblowing balloon 222, second layer 224 may be locally thinned to form arecess 236 in the area of the planned balloon using laser micromachiningor the like. The tool 234 may have a recess 238 and can engage thematerial of second layer 232 around the recess. The material of secondlayer 232 adjacent the recess may be heated, and sufficient pressure maybe applied to the surface of the second layer opposed to the tool toexpand and urge the material of the layer against the tool within therecess. The recess 238 may have an undulating surface as schematicallyshown so that when the substrate is assembled and curved the inflatedballoon will be pre-formed to curve about the arc angle α. The variationin balloon diameter described above can also be defined in the recess238 of tool 234, with the tool optionally having a plurality of recessesfor other balloons of the balloon array structure, passages to apply avacuum or port gasses from between the balloon material and tool. Thetool may be formed using any of a variety of 3-D printing techniques,laser micromachining, or many of the other techniques described herein.

A number of inflation fluid supply system component arrangements for usein any or all of the articulation, stiffening, and/or bend controlsystems described herein can be understood with reference to FIGS.7A-7F. As noted above, the valves, ports, and the like may be includedin a proximal housing, may be incorporated into a substrate of theballoon array, or a combination of both. First addressing a simpleinflation control arrangement 240 of FIG. 7A, a single on/off gate valve242 may be along a fluid flow path between a fluid source 244 and aballoon 246. A limited flow exhaust port 248 remains open, and openingof valve 242 allows sufficient fluid from the source to inflate balloondespite a limited flow of fluid out of limited port 248, which can havean orifice or other fixed flow restriction. When gate valve 242 isclosed, flow out of the limited port 248 allows the balloon to deflate.The two-valve arrangement 250 of FIG. 7B uses two separate gate valves242 to independently control flow into and out of the balloon, therebylimiting the loss of fluid while the balloon remains inflated and alsopreventing deflation speed from being limited more than might otherwisebe desired. While the inflow channel into the balloon and out of theballoon are shown as being separate here, both valves may instead becoupled to the inflow channel, with the deflation valve typically beingbetween the inflation valve and the balloon.

A two-way valve arrangement 260 is shown in FIG. 7C, with a two wayvalve 262 having a first mode that provides fluid communication betweensupply 244 and balloon 246, and a second mode that provides fluidcommunication between the balloon and an exhaust port 264 (while thesupply is sealed to the port and balloon).

A ganged-balloon arrangement 270 is shown in FIG. 7D, with a two wayvalve 262 between supply 244 and a plurality of balloons 272, 274, 276,. . . . Such an arrangement allows a number (typically between 2 and 10balloons) to be inflated and deflated using a single valve, which may beused when a subset of balloons are often to be inflated, such as forelongation of an axial segment, for imposing a desired base curvature(to which other incremental axial bend components may be added), forimposing multi-balloon incremental axial bend components or the like.

A transfer-bend valve arrangement 280 is shown in FIG. 7E, with two wayvalves 262 i, 262 ii each allowing inflation of an associated balloon246 i, 246 ii, respectively. Additionally, a transfer gate valve 242between balloons 246 i and 246 ii allows inflation fluid to flow fromone (or more) balloon to another (one or more) balloon. This may allow,for example, a bend associated with one balloon to be transferredpartially or fully to a bend associated with a different balloon inresponse to environmental forces against the flexible body, such as whena catheter is pushed axially within a bent body lumen (so that the bendtransfers axially), when a catheter is rotated within a bent body lumen(so that the bend transfers laterally), a combination of the two, or thelike. A transfer valve may also be used, for example, help determine acatheter shape that limits forces imposed between a surrounding lumenalwall and the catheter structure. For this (and potentially otheradvantageous uses) a valve may be opened between a full-inflationpressure source and one or more balloon to initially inflate suchballoon(s) so that the catheter is urged toward an initial state. Atleast one transfer valve may be opened between the inflated balloon(s)and one or more uninflated balloons so as to drive the catheterconfiguration having a bend. If the tissue surrounding the bend (andinternal balloon compression structures of the catheter) urge deflationof the inflated balloons with sufficient force, and if the surroundingtissue urge the catheter to assume another bend associated with thoseuninflated balloon(s) so as to mitigate the internal balloon compressionstructures of the catheter, inflation fluid can be forced from theinflated balloon(s) to the uninflated balloon(s), and the catheter canthen allow the tissue to assume a more relaxed shape. Interestingly,changes in the catheter bend configuration associated with inflationfluid flowing between balloons may at least in part be pseudo-plastic,with fluid flow resistance limiting elastic return to the prior state.Use of a flow modulating transfer valve (as opposed to a simple on/offgate valve) may allow corresponding modulation of this pseudo-plasticbend state change. Alternatively, a transfer valve and associatedchannel may have a tailored flow resistance (such as an orifice orcontrolled effective diameter section) to tailor the pseudo-plasticproperties.

A multi-pressure valve arrangement 290 is shown in FIG. 7F, in which atwo-way valve allows inflation or deflation of an associated balloonfrom a full inflation supply 244 i as described above. Alternatively, apartial inflation fluid supply 244 ii can direct fluid at a lower(optionally fixed) partial inflation pressure to the same balloon. Thepartial inflation pressure may be insufficient to overcome the bias ofthe helical coil and the like toward balloon deflation and astraight-coil configuration, and thus may not alone bend the flexiblebody (absent tissue or other environmental forces against the catheter),but can selectively reduce the strength of the catheter against a bendassociated with the partially inflated balloon. Alternatively, thepressure may be sufficient to partially inflate the balloon and induce aportion of a full-inflation bend. Regardless, one or more partialinflation fluid supply pressures may be provided using one or moreassociated valves, with the inflation fluid being a one or moreincremental pressures between a full balloon inflation pressure andatmospheric pressure. Note that partial inflation may alternatively beprovided by modulating a variable valve for a limited inflation time soas to control total fluid flow quantity to one or more balloons, bycontrolling one or more on/of pulse cycles times of a gate valve, or thelike. Still other combinations of inflation fluid directing componentsmay be included in many embodiments, with at least some of thecomponents (and particularly channels between the valves and theballoons) being integrated into the balloon array, at least some of thecomponents (particularly the pressurized fluid canister or other source)being in a proximal housing coupled to a proximal end of the catheter orother flexible body, and others (portions of the channels, valves,ports, valve actuation circuitry, etc.) being in either or distributedin both. In some embodiments, a non-actuating positive inflation fluidpressure (greater than the atmosphere surrounding the balloon array butinsufficient to separate loops of a coil) may be maintained in some orall of the balloons that are in a nominally non-inflated state. This maypre-inflate the balloons so that the fluid partially fills the balloonand the balloon wall expands where it does not engage the coil,decreasing the quantity of fluid that flows to the balloon to achievefull inflation.

A wide variety of desirable inflation fluid supply system capabilitiescan be provided using one or more valve component arrangements describedabove. For example, rather than including a separate partial inflationpressure fluid supply, a transfer valve can be used to first fullyinflate a first balloon, after which a transfer valve can be used totransfer a portion of the fluid from the inflated balloon to one or moreother balloons, resulting in gang partial inflation of multipleballoons. A fluid supply system may have a network of channels with acombination of inflation gate valves and deflation gate valves so as toallow selective inclusion of any of a plurality of individual balloonsin an inflated subset, selected ganged balloons that pre-define some orall of the members of subsets that will be used simultaneously, and thelike.

An exemplary embodiment of a helical balloon array structure 282 can beseen in FIGS. 7G-7I. Helical array 282 can be formed in a flatconfiguration and rolled helically to a cylindrical configuration.Balloons 284 may be initially formed using relatively conventionalnon-compliant balloon forming techniques, optionally with offset ends soas to facilitate affixing the balloons and inflation/deflation channels288 to a substrate 286. Balloons 284 may be relatively short (withlength/diameter aspect ratios of 4 or less), and/or may be formed ormodified so as to curve along the balloon axis (to accommodate anarc-angle curvature when the substrate is rolled and the balloons extendcircumferentially, as noted above regarding FIG. 12). Balloons 284 andtubular structures initially defining inflation/deflation channels 288may be affixed to a first substrate layer 292 using adhesive bonding,with the channels optionally comprising commercially available fusedsilica tubing. In this embodiment, balloons 284 define a 1×N array inthe flat configuration, N optionally being between 4 and 80, preferablybeing between 8 and 32, and in at least some embodiments being 16 or 24.

Elongate axes of balloons 284 are oriented so as to extendcircumferentially at an angle corresponding to a pitch angle of thehelical coil of the skeleton to be used with helical array structure 282(which will often be different than the helical pitch of substrate 286)and are positioned so that every 4^(th) (or optionally every 3^(rd))balloon is axially aligned when the substrate is rolled in thecylindrical configuration. Hence, in the rolled cylindricalconfiguration balloons 284 can define a 4×N array (or 3×N) array toallow being in 4 (+/−X and +/−Y) lateral orientations. Balloon migrationinhibiting features or tabs 294 may be affixed to the balloons (such asbeing adhesively bonded while the balloons are inflated) so that theballoons, substrate, and tabs together define coil loop receptacles 298.A second substrate layer may optionally be formed and affixed over theassembly so that the balloons, channels, and any tabs are disposedbetween the layers. Extensions of the substrate may be used asquick-disconnect fluid couplers to provide fluid communications betweenchannels 288 and the valves and fluid supply of the proximal housing.The helical substrate may facilitate flexing and elongation of thecatheter assembly, and the array can be assembled with limited tooling.Suitable fluid supply header systems may be fabricated usingcommercially available 3-D printing techniques, with the valvescomprising commercially available electrically actuated structuresmounted to the printed header and under control of a standardmicroprocessor.

Referring now to FIG. 8, components of an exemplary catheterarticulation system 292 can be seen, with these components generallybeing suitable for use in catheter system 1 of FIG. 1. In thisembodiment, a catheter 294 has a distal articulated portion 296, withthe articulated portion optionally including axially separatearticulation sub-portions or segments, and alternatively having a singlerelatively continuously articulated length. An insertion sheath/inputassembly 295 is included in the system user interface, and both assembly295 and the proximal end of catheter 294 are detachably coupleable witha proximal housing 298 using flexible cables (and quick-disconnectcouplers), with the housing containing a battery, a processor, areplaceable compressed fluid cartridge, valves, and the like. Housing298 also includes or contains additional components of the userinterface, and is sized for positioning by a single hand of a user, butneed not be moved during use of catheter 294. Commands to effectautomated bending and elongation of distal portion 296 during use mayoptionally be input into the system by bending and axial insertion ofinput 297 relative to a proximal body of the introducer sheath, therebyemploying manual movements of the user which are already familiar tophysicians that employ catheter-based diagnostic and therapeutic tools.

Regarding some of the user interface components of articulation system292, use of input 297 for controlling the articulation state of catheter294 will be described in more detail hereinbelow. In addition to input297, a number of additional (or alternative) user interface componentsmay be employed. As generally indicated above, the user interface mayinclude a housing affixed to a proximal end of catheter 294, with thehousing having a joystick as described above regarding FIG. 1-1.Trackballs or touchpads may be provided in place of a joystick, and asthe catheters and other structures described herein may have more thantwo degrees of freedom, some embodiments may include two offsetjoysticks, with a more proximal joystick on the handle being used tolaterally deflect the catheter along a proximal X-Y segment and a moredistal joystick of the same handle being used to laterally deflect thecatheter along a more distal X′-Y′ segment. These two deflections may beused to enter movement commands in a manner analogous to positioning ofa robotic base using the first joystick and then articulating a wristmounted to that base with the second joystick, with the joysticksproviding either position or velocity control input to the cathetersystem. An input wheel with a surface that rolls along the axis of thehousing can be used for entering axial elongation movement commands, andthe housing may have a circumferential wheel that can be turned by thesystem user to help provide a desired alignment between an orientationof the housing relative to the lateral deflections of the catheter asseen in the remote imaging display. Still further alternative userinterface systems may employ computer workstations such as those ofknown robotic catheter or robotic surgical systems, which may includeone or more 3-D joysticks (optionally including an input allowing 4D,5D, or even more degrees of freedom), housings mimicking those ofmechanically steerable catheter systems, or the like. As seen in theembodiment of FIG. 8, still further optional components include atouchscreen (which may show a graphical representation of distalarticulated portion 296 (one or more segments of which can betouch-selected and highlighted so that they articulate in response tomovement of input 297), pushbuttons, or the like. Still furtheralternative user interface components may include voice control, gesturerecognition, stereoscopic glasses, virtual reality displays, and/or thelike.

Referring now to FIG. 9, selected components of an articulated portion302 of an articulated catheter 304 can be seen in more detail. Aplurality of inflated balloons 306 are offset from an axis 308 ofcatheter 304 along a first lateral orientation +X, so that the balloonsurge corresponding pairs of axial (proximal and distal) surfaces on theloops of coil 310 apart. This urges the coil to bend away from inflatedballoons 306 away from the +X orientation and toward the −X lateralorientation. Uninflated balloons 312 a, 312 b, and 312 c are offset inthe lateral −X, −Y, and +Y orientations, respectively, allowingselective inflations of differing subsets of these balloons to bend axis308 in differing directions. Inflation of opposed balloons (such as −Xand +X, or −Y and +Y, or both) may elongate coil 314 along axis 308.Note that a distal portion of coil 314 has been omitted from the drawingso that the arrangement of the balloons can be more clearly seen. Thisembodiment shows relatively standard offset balloon shapes, with theaxes of the balloons bent to follow the coil. In this and otherembodiments, a single balloon between coils may impose a bend in axis308 in a range from 1 to 20 degrees, more typically being in a rangefrom 2½ to 15 degrees, and often being from 6 to 13 degrees. To allow asingle inflation lumen to achieve greater bend angles, 2, 3, 4, or moreballoon inflation lumens or ports adjacent the balloons may be in fluidcommunication with a single common fluid inflation lumen.

Referring now to FIGS. 10A-10D, an exemplary integrated balloon arrayand array substrate design and fabrication process can be understood. Asseen in FIGS. 10A and 10B, a cylinder 318 is defined having a diametercorresponding to a helical coil axis 320 of coil 310, with the coil axistypically corresponding to the central axis of the coil wire (so thatthe helical axis winds around the central axis of the elongate body).Desired balloon centerlines 322 are here defined between loops of thecoil. Alternative balloon centerlines may extend along the coil axis, ascan be understood with other embodiments described below. A flat pattern324 of the balloon centerlines 322 can be unwrapped from cylinder 318,with the flat pattern optionally forming a repeating pattern extendingalong a helical wrap of the cylinder, the helical pattern unwrapoptionally being counterwound relative to coil 310 and typically havinga pitch which is greater than that of the coil. As can be understoodwith reference to FIGS. 10C and 10D, the repeated flat pattern 324 canbe used to define a repeating substrate pattern 326, with the substratepattern here including, for each balloon in this portion of the array, aballoon portion 328, a multi-lumen channel portion 330, and a connectorportion 332 for connecting the balloon to the multi-lumen channelportion. The connector portions and balloons here extend from a singleside of the multi-lumen channel portion; alternative embodiments mayhave connector portions and balloons extending from both lateral orcircumferential sides. The loops of the substrate helix may alsooverlap. In other embodiments, the flat pattern (and associatedsubstrate and multi-lumen channels) may wind in the same direction asthe coil, with the balloons and channel structures optionally extendingalong a contiguous strip, the balloons optionally having channels alongone or both axial sides of the strip and the balloons protrudingradially from the strip and between the loops of the coil so thatconnector portions 332 may optionally be omitted. Such embodiments maybenefit from a thicker and/or polymer coil. Regardless, the helicalballoon array structure may facilitate lateral bending of the catheteralong its axis and/or axial elongation of the catheter without kinkingor damaging the substrate material along the fluid flow channels, as thesubstrate loops may slide relative to each other along an inner or outersurface of coil 310 (often within a sealed annular space between innerand outer sheaths bordering the inner and outer surfaces of thecatheter).

Advantageously, the substrate pattern may then be formed in layers asgenerally described above, with at least a portion (often the majority)of each balloon being formed from sheet material in a first or balloonlayer 334 (optionally by blowing at least a portion of the balloon fromsuitable sheet material into a balloon tool) and some or all of thechannels being formed from sheet material in a second or channel layer336. The layers can be bonded together to provide sealed fluidcommunication between the balloons and the other components of the fluidsupply system, with the outline shapes of the balloon portions 328,connector portions 332, and channel portions being cut before bonding,after bonding, or partly before and partly after. Note that a portion ofthe balloon shape may be imposed on the channel layer(s) and that aplurality of channel layers may be used to facilitate fluidcommunication between a plurality of helically separated balloons(including balloons along a single lateral orientation of the assembledcatheter) and a common fluid supply channel. Similarly, a portion (oreven all) of the channel structure might alternatively be imposed on theballoon layer, so that a wide variety of architectures are possible.Formation of multiple balloons 334 and channels 330, and bonding of thelayers can be performed using parallel or batch processing (with, forexample, tooling to simultaneously blow some or all of the balloons fora helical balloon array of an articulation sub-portion, a lasermicromachining station that cuts multiple parallel channels,simultaneous deposition of adhesive materials around multiple balloonsand channels), or sequentially (with, for example, rolling toolingand/or roll-by stations for balloon blowing, laser cutting, or adhesiveapplying tooling), or a combination of both. The number of balloonsincluded in a single helical substrate pattern may vary (typically beingfrom 4 to 80, and optionally being from 4 to 32, and often being from 8to 24). The balloons may be spaced for positioning along a singlelateral catheter bending orientations, along two opposed orientations,along three orientations, along four orientations (as shown), or thelike. Channel portion 330 may terminate at (or be integrated with) aninterface with a multi-channel cable 334 that extends proximally alongthe coil (and optionally along other proximal balloon array portionsformed using similar or differing repeating balloon substrate patterns).A wide variety of alternative balloon shapes and balloon fabricationtechniques may be employed, including blowing a major balloon portionfrom a first sheet material and a minor portion from a second sheetmaterial, and bonding the sheets surrounding the blow portions togetherwith the bond axially oriented (as shown in FIG. 10) so that the sheetsand substrate layers are oriented along a cylinder bordering the coil,or with the bond radially oriented so that the sheet material adjacentthe bonds is connected to adjacent substrate by a bent connector portionor tab.

As can be understood with reference to the balloon structures of FIG.10E-10I (and more generally as illustrated and described herein), a widevariety of alternative balloon shapes and balloon fabrication techniquesmay be employed. Balloon 340 of FIG. 10E may be formed by blowing amajor balloon portion 342 from a first sheet material and a minorportion 344 from a second sheet material, and by bonding the sheetssurrounding the blow portions together. The bond may be axially oriented(as shown in FIGS. 10A-10D) so that the sheets and substrate layers areoriented along a cylinder bordering the coil, or radially oriented (asshown in FIGS. 6L and 10E), with the radially oriented sheet materialadjacent the bonds being connected to the other array substrate by abent connector portion or tab. The balloons may have substantiallycircular cross-sections with smaller diameters near the ends asdescribed above. While bonded balloons may optionally be formed byforming similar corresponding expanded regions 346 in two sheets orlayers (as shown in FIG. 10F), there may be advantages to forming aballoon cross-section primarily in a first sheet 348 and bonding that toa second sheet with a smaller (or non) expanded region 350 (as shown inFIG. 10G). In particular, the strength of the bond may be enhanced byfolding and bonding bordering substrate material adjacent the balloonshape to the wall of the balloon as shown in FIG. 10H; this may befacilitated when a major portion of the balloon is on one side of thebond. Still further alternatives are possible, including providing asecond balloon wall layer surrounding any of the bonded balloons shownor described herein, as can be understood with reference to FIG. 10I.The bonded balloon and second balloon wall may be formed separately withsimilar shapes which will tend to maintain alignment between the walls,decreasing any reliance on high-strength bonding between the balloonmaterials.

Referring now to FIGS. 11A and 11B, an alternative coaxial balloon/coilarrangement can be understood. In these embodiments, balloons 364 aremounted over a coil 366, with a plurality of the balloons typicallybeing formed from a continuous tube of material that extends along thehelical axis of the coil (see helical axis 320 of FIG. 10A). The balloonmaterial will generally have a diameter that varies locally, with theballoons being formed from locally larger diameter regions of the tube,and the balloons being separated by sealing engagement between the tubematerial and coil therein at locally smaller diameters of the tube. Thevariation in diameter may be formed by locally blowing the balloonsoutward from an initial tube diameter, by locally heat-shrinking and/oraxially stretching the tube down from an initial tube diameter, or both,and adhesive or heat-bonding between the tube and coil core therein mayenhance sealing. In alternative embodiments, metal rings may be crimpedaround the tubular balloon material to affix (and optionally seal) thetube to the underlying helical coil, with the rings and crimpingoptionally employing marker band structures and associated techniques.Some or even all of the variation in diameter of the balloon materialalong the coil may be imposed by the crimped rings, though selectiveheat shrinking and/or blowing of the balloons and/or laser thermalbonding of the balloon to the coil may be combined with the crimps toprovide the desired balloon shape and sealing. Regardless, fluidcommunication between the inner volume of the balloon (between theballoon wall and the coil core) may be provided through a radial port toan associated lumen within the coil core. As can be understood withreference to coil assembly 360 of FIG. 11A, the balloons may have outersurface shapes similar to those described above, and may similarly bealigned along one or more lateral bending orientations. As can beunderstood with reference to assemblies 360 and 362 of FIGS. 11A and11B, bend angles and radii of curvature of the catheter adjacent theballoon arrays may be determined by an axial spacing (and/or number ofloops) between balloons, and/or by selective inflation of a subset ofballoons (such as by inflating every other balloon aligned along aparticular lateral axis, every third aligned balloon, every fourthaligned balloon, and so on).

Referring now to FIGS. 11C, 11D, and 11E, alternative coaxialballoon/coil systems may take a variety of differing forms. In FIG. 11C,a plurality of helical structures 370, 372 are interleaved together. Onehelical structure 370 here takes the form of a simple helical coil andfunctions as an element of the structural backbone of a catheter,compressing balloons between loops of the coil and the like. The otherhelical structure includes balloons 374 over a helical core, with one ormore lumens extending within the helical core. Note that the helicalcore supporting the balloons may or may not include a structural coilwire or the like, so that the components that provide fluid transmissionfunctionality may be separated from or integrated with the structuralcomponents. In the embodiment of FIG. 11D, a plurality of helicalstructures each have associated balloons, which may be inflatedseparately or together. In some embodiments, balloons aligned along oneor more lateral orientations may be on a first helical structure, andballoons along one or more different orientations may be on a secondinterleaved helical structure, so that fluid transmission through ahelical core may be simplified. In other embodiments (as can beunderstood with reference to 4-direction coaxial balloon/coil 380 ofFIG. 11E), balloons subsets aligned along the differing lateralorientations may be mounted to a single helical core.

Referring now to FIGS. 11F and 11G, exemplary multi-lumen helical corestructures can be understood. In these embodiments, an extruded polymersheath is disposed over a structural coil wire 382, with the sheathhaving multiple peripheral lumens, such as 4 or 6 lumen sheath 384 or 16lumen sheath 386. A tube of balloon material may be positioned over thesheath, with larger diameter portions of the tube forming balloons 388,and smaller diameter portions 390 engaging the sheath therein so as toseal between the balloons. A port 392 can be formed through the wall ofthe sheath into one of the lumens (typically prior to completion of theballoon structure) so that the interior of the balloon is in fluidcommunication with that associate lumen. The lumen may be dedicated tothat one balloon, or will often be coupled to (and used to inflate) oneor more balloons as a group or sub-set, with the group often beingaligned along a lateral orientation of the coil so as to bend the coilin a common direction, opposed so as to axially elongate the coil, orthe like. As can be understood by comparison of FIGS. 11F and 11G, thenumber of lumens in a helical core may impact the inflation lumen size(and response time), so that there may be benefits to using separateactuation sub-portions and running fluid flow channels outside thehelical core. Where large numbers of lumens or complex lumen networksand geometries are desired, the core may include a first sheath layerhaving an outer surface which is processed (typically lasermicromachined) to form some or all of the channels. A second sheathlayer can be extruded or bonded radially over the first layer tolaterally seal the channels. Similar processing of the outer surface ofthe second layer (and optionally subsequent layers) and extrusion orbonding of a third layer (and optionally subsequent layers) radiallyover the second layer may also be performed to provide multi-layeredlumen systems.

Referring now to FIG. 12, further separation of functionality amongexemplary catheter components can be understood with reference to anexploded assembly 400, which shows an axial portion of an articulatedcatheter, the components here being laterally displaced from each other(and from their assembled coaxial positioning). The fluid-containingcomponents of this portion are preferably contained between an innersheath 402 and an outer sheath 404, with these sheaths being sealed toeach other proximally and distally of the balloon array (or of someportion of the array). By drawing a vacuum between the sealed inner andouter sheaths (optionally using a simple positive syringe pump or thelike) and by monitoring of the vacuum with a pressure sensing circuitcoupled to a fluid supply shut off-valve, integrity of the fluidtransmission and drive components within the patient body can beensured, and inadvertent release of drive fluid within the patient canbe inhibited.

Still referring to FIG. 12, a coaxial helical coil/balloon assembly 406is disposed radially between the inner and outer sheaths 402, 404. Theinner and/or outer sheaths may be configured so as to enhance radialstrength and axial flexibility, such as by including circumferentialfibers (optionally in the form of a polymer or metallic braid, loops, orwindings), axial corrugations, or the like. As described above, balloonsof assembly 406 are mounted to a helical core along a helical axis. Atleast one lumen extends along the helical core and allows the balloonson the core to be inflated and deflated. To help maintain axialalignment of the loops of assembly 406 an alignment spacer coil 408 isinterleaved between the assembly loops. Spacer coil 408 has opposedsurfaces with indented features so that axial compressive forces (fromthe environment or inflation of the balloons) squeezes the alignmentspacer and keeps the assembly balloons and adjacent loops from beingpushed radially out of axial alignment, as can be further understoodwith reference to FIGS. 6K and 6L and the associated text. Note that anyof the structural skeleton or frame elements described herein (includingthe push-pull frames described below) may include balloon/frameengagement features (such as indentations along balloon-engagingsurfaces), and/or separate balloon/frame interface bodies may beprovided between the frames and the balloons to help maintain alignmentballoon/frame alignment or to efficiently transmit and distribute loadsor both. Note that compression between loops of assembly 406 may beimposed by the coil, by the spacer, by the inner and/or outer sheath, bya pullwire, or by a combination of two or more of these. Note also thatalternative embodiments may replace the balloons mounted on the coilwith balloons between loops of the coil coupled with a layered arraysubstrate such as those shown in FIGS. 10C and 10D, optionally with apair of alignment spacer coils on either axial surface of the balloons(and hence between the balloons and the coil). Still furtheralternatives include multiple interleaved coil/balloon assemblies,and/or other components and arrangements described herein.

As there may be a large total number of balloons in the overall balloonarray of some embodiments, and as those arrays may be separated axiallyinto articulated sub-portions of an overall catheter (or otherarticulated elongate body), and as the available space within the coilcore of coil/balloon assembly 406 may be limited, it may be advantageousto have one or more separate structures extending axially within theannular space between inner and outer sheaths 402, 404. Those separatestructures can have additional fluid inflation channels that areseparate from the fluid inflation channels of the coil/balloon assemblyor assemblies, and that can be used for inflating balloon articulationarrays that are mounted distally of the coil/balloon assembly 406.Toward that end, thin flat multi-lumen helical cable structures 410 a,410 b may be disposed in the space radially between the coil/balloonassembly 406 and outer sheath 404, and/or between the coil/balloonassembly and inner sheath 402. Cables 410 may comprise a series of smalldiameter tubular structures (optionally comprising PET or fused silicawith appropriate cladding) which may or may not be affixed together andare in a side-by-side alignment, a multichannel structure formed bymicromachining and bonding layers (as described above), a multi-lumenextrusion having an elongate cross-section, or the like. Each cable 410a, 410 b of a particular axial segment may be coupled to a core of acoil/balloon assembly for a more distal articulated axial segment. Ahelical or serpentine configuration of the cables may facilitate axialbending and/or elongation without stressing the cables, and the numberof cables along an articulation segment may range from 0 (particularlyalong a distal articulation segment) to 10. Note that a number ofalternative arrangements are also possible, including separating thecables from the coil/balloon assembly with an intermediate sheath,enhancing flexibility by using a number of separate fused silica tubeswithout bundling subsets of the tubes into cables, and the like.

As can be understood with reference to FIG. 13A, one or more stiffeningballoons may be incorporated into the cable structure, with thestiffening balloons of each segment optionally being in fluidcommunication with a common supply lumen, and optionally with a commonsupply lumen for one, some, or all other segments. In the exemplarycable structure shown, the stiffening balloon may comprises a tubularmaterial disposed around a multi-lumen cable extrusion, and may beinflated using a port within the tube into a selected lumen of theextrusion. The stiffening balloon tube may be sealed to the cableextrusion or the like proximally and distally of the port, and may havean expandable length sufficient to extend along some or all of an axialarticulation segment or sub-portion. The cables and any stiffeningballoons thereon may extend axially between the coil and an inner orouter sheath, inflation of such stiffening balloons can induce radiallyengagement between the stiffening balloons and the coil, inhibitingchanges in the offsets between loops and thereby stiffening the catheteragainst axial bending. The stiffening balloon may be inflated atpressures significantly lower than the bending or elongation actuationballoons, and may be used along segments or even catheters lackingbending or elongation balloons altogether. Alternatively, the cable mayoften be omitted, particularly where the core along a single segment canencompass sufficient channels for the desired degrees of freedom of thecatheter.

Referring now to FIGS. 13B and 13C, one exemplary transition from amulti-lumen helical core to a cable can be understood. The helical corehere again includes a coil wire 420 surrounded by an extrudedmulti-lumen polymer body 422, with the body here having lumens 424 thattwist around the coil wire. While only 3 lumens are shown, the spacinghere would allow for 9 twisting lumens (the other lumens being omittedfor simplicity). Radial ports from 8 of these lumens would allow, forexample, independent inflation control over 8 balloons (or groups ofballoons), and the ninth lumen may be used to draw and monitor a vacuumin a sealed axial segment around these balloons and between inner andouter sheaths (both as described above). Additionally, in the spacebetween two adjacent lumens a notch 426 extends radially part waythrough body 422, with the notch winding around the core axis.Proximally of the most proximal balloon mounted on body 422, body 422 isseparated at notch 426 and the body material and the lumens 424 thereinare unwound from the coil wire 420. This unwound material can beflattened to form a multi-lumen cable as explained above regardingcables 410, 410 a, and 410 b of FIGS. 12 and 13, with the cableextending proximally from a helical multi-lumen core without having torely on sealed tubular joints or the like. Alternative bonded joints orconnectors between an extrusion, a single or multi-lumen tubularstructure, and/or a layered channel system may also be employed.

Referring now to FIG. 13, an exemplary catheter 430 has an articulatedportion 432 that includes a plurality of axially separate articulatedsegments or sub-portions 434 a, 434 b, 434 c, and 434 d. Generally, theplurality of articulation segments may be configured to facilitatealigning a distal end of the catheter with a target tissue 436. Suitablearticulation segments may depend on the target tissue and plannedprocedure. For example, in this embodiment the articulation segments areconfigured to accurately align a distal end of the catheter with theangle and axial location of the native valve tissue, preferably for anypatient among a selected population of patients. More specifically, thecatheter is configured for aligning the catheter axis at the distal endof the catheter with (and particularly parallel to) an axis of thetarget tissue, and (as measured along the axis of the catheter) foraxially aligning the end of the catheter with the target tissue. Suchalignment may be particularly beneficial, for example, for positioning aprosthetic cardiac valve (optionally an aortic valve, pulmonary valve,or the like, and particularly a mitral valve) with tissues of oradjacent a diseased native valve. Suitable catheter articulationcapabilities may also, in part, depend on the access path to the targettissue. For alignment with the mitral valve, the catheter may, forexample, be advanced distally into the right atrium via the superior orinferior vena cava, and may penetrate from the right atrium through theseptum 438 into the left atrium. Suitable transceptal access may beaccomplished using known catheter systems and techniques (thoughalternative septal traversing tools using the articulated structuresdescribed herein might alternatively be used). Regardless, to achievethe desired alignment with the native valve tissue, the catheter may beconfigured to, for example: 1) from distally of (or near) the septum,form a very roughly 90 degree bend (+/−a sufficient angle so as toaccommodate varying physiologies of the patients in the population); 2)extend a distance in desired range in three dimensions, including a)apically from the septal penetration site and b) away from the plane ofthe septal wall at the penetration; and 3) orient the axis of thecatheter at the distal end in three dimensions and into alignment withthe native valve tissue.

To achieve the desired alignment, catheter 430 may optionally provideconsistent multi-axis bend capabilities as well as axial elongationcapabilities, either continuously along the majority of articulatableportion 432 of catheter 430, or in articulated segments at regularintervals extending therealong. Alternative approaches may employ morefunctionally distinguished articulation segments. When present, eachsegment may optionally have between 4 and 32 balloons, subsets of theballoons within that segment optionally being oriented along from 1 to 4lateral orientations. In some embodiments, the axis bending balloonswithin at least one segment may all be aligned along a single bendorientation, and may be served by a single inflation lumen, often servedby a modulated fluid supply that directs a controlled inflation fluidvolume or pressure to the balloons of the segment to control the amountof bending in the associated orientation. Alternative single lateralbending direction segments may have multiple sets of balloons served bydifferent lumens, as described above. For example, segments 434 a and434 b may both comprise single direction bending segments, each capableof imposing up to 60 degrees of bend angle and with the former having afirst, relatively large bend radius in the illustrated configuration dueto every-other axial balloon being inflated (as can be understood withreference to FIG. 11A) or due to inflation with a limited quantity ofinflation fluid. In segment 434 b, all but the distal-most four balloonsmay be inflated, resulting in a smaller bend radius positioned adjacentsegment 434 a, with a relatively straight section of the catheter distalof the bend. Segment 434 c may have balloons with four different bendorientations at a relatively high axial density, here having selectedtransverse balloons (such as 6 +X balloons and 2 −Y balloons) inflatedso as to urge the catheter to assume a shape with a first bend componentaway from the septal plane and a second bend component laterally awayfrom the plane of the bends of segments 434 a and 434 b. Segment 434 dmay comprise an axial elongation segment, with opposed balloons in fluidcommunication with the one or more inflation fluid supply lumen of thissegment. Axial positioning of the end of the catheter may thus beaccurately controlled (within the range of motion of the segment) byappropriate transmission of inflation fluid. Advantageously, suchspecialized segments may limit the number of fluid channels (and thecost, complexity and/or size of the catheter) needed to achieve adesired number of degrees of freedom and a desired spatial resolution.It should be understood that alternative segment arrangements might beemployed for delivery of a prosthetic heart valve or the like, includingthe use of three segments. The valve might be positioned using athree-segment system by, for example, inserting the catheter so that theseptum is positioned along the middle of the three segments, ideallywith the catheter traversing the septum at or near the middle of themiddle segment.

Referring now to FIGS. 14A-14C, a still further embodiment of anarticulated catheter includes first and second interleaved helicalmulti-lumen balloon fluid supply/support structures 440 a, 440 b, alongwith first and second resilient helical coils 442 a, 442 b. In thisembodiment, a series of balloons (not shown) are mounted around each ofthe multi-lumen structures, with the balloons spaced so as to be alignedalong three lateral bending orientations that are offset from each otheraround the axis of the catheter by 120 degrees. Six lumens are providedin each multi-lumen structure, 440 a, 440 b, with one dedicatedinflation lumen and one dedicated deflation lumen for each of the threelateral bending orientations. Radial fluid communication ports betweenthe lumens and associated balloons may be provided by through cutsthrough pairs of the lumens.

By spacing the cuts 444 a, 444 b, 444 c, as shown, and by mountingballoons over the cuts, the inflation and deflation lumens can be usedto inflate and deflate a subset of balloons aligned along each of thethree bending orientations. Advantageously, a first articulated segmenthaving such a structure can allow bending of the catheter axis in anycombination of the three bend orientations by inflating a desired subsetof the balloons along that segment. Optionally, the bend angle for thatsubset may be controlled by the quantity and/or pressure of fluidtransmitted to the balloons using the 6 lumens of just one multi-lumenstructure (for example, 440 a), allowing the segment to function in amanner analogous to a robotic wrist. Another segment of the catheteraxially offset from the first segment can have a similar arrangement ofballoons that are supplied by the 6 lumens of the other multi-lumenstructure (in our example, 440 b), allowing the catheter to position andorient the end of the catheter with flexibility analogous to that of aserial wrist robotic manipulators. In other embodiments, at least someof the balloons supplied by the two multi-lumen structures may axiallyoverlap, for example, to allow increasing bend angles and/or decreasingbend radii by combining inflation of overlapping subsets of theballoons. Note also that a single lumen may be used for both inflationand deflation of the balloons, and that multi-lumen structures of morethan 6 lumens may be provided, so that still further combinations thesedegrees of freedom may be employed.

In the embodiment illustrated in the side view of FIG. 14A and in thecross-section of FIG. 14B, the outer diameter of the helical coils isabout 0.130 inches. Multi-lumen structures 440 a, 440 b have outerdiameters in a range from about 0.020 inches to about 0.030 inches(optionally being about 0.027 inches), with the lumens having innerdiameters of about 0.004 inches and the walls around each lumen having aminimum thickness of 0.004 inches. Despite the use of inflationpressures of 20 atm or more, the small diameters of the lumens helplimit the strain on the helical core structures, which typicallycomprise polymer, ideally being extruded. Rather than including aresilient wire or the like in the multi-lumen structure, axialcompression of the balloons (and straightening of the catheter axisafter deflation) is provided primarily by use of a metal in coils 442 a,442 b. Opposed concave axial surfaces of coils 442 help maintain radialpositioning of the balloons and multi-lumen structures between thecoils. Affixing the ends of resilient coils 442 and balloonsupply/support structures 440 together to the inner and outer sheaths atthe ends of the coils, and optionally between segments may help maintainthe helical shapes as well. Increasing the axial thickness of coils 442and the depth of the concave surfaces may also be beneficial to helpmaintain alignment, with the coils then optionally comprising polymerstructures. Still other helical-maintaining structures may be includedin most or all of the helical embodiments described herein, includingperiodic structures that are affixed to coils 442 or other helicalskeleton members, the periodic structures having protrusions that extendbetween balloons and can engage the ends of the inflated balloon wallsto maintain or index lateral balloon orientations.

Many of the embodiments described herein provide fluid-drivenarticulation of catheters, guidewires, and other elongate flexiblebodies. Advantageously, such fluid driven articulation can rely on verysimple (and small cross-section) fluid transmission along the elongatebody, with most of the forces being applied to the working end of theelongate body reacting locally against the surrounding environmentrather than being transmitted back to a proximal handle or the like.This may provide a significant increase in accuracy of articulation,decrease in hysteresis, as well as a simpler and lower cost articulationsystem, particularly when a large number of degrees of freedom are to beincluded. Note that the presence of relatively high pressure fluid,and/or low temperature fluid, and/or electrical circuitry adjacent thedistal end of an elongate flexible body may also be used to enhance thefunctionality of tools carried by the body, particularly by improving oradding diagnostic tools, therapeutic tools, imaging or navigationstools, or the like.

Referring now to FIG. 15, a radially elongate polymer helical ballooncore structure 450 generally has a cross section with a radial thickness452 that is significantly greater than its axial thickness 454. Radialthickness 452 may optionally be, for example 80% or more of the inflateddiameter of the surrounding balloon, while axial thickness 454 may bebetween 20% and 75% of the inflated diameter. As compared to a circularcore cross-section, such an elongate cross-section provides additionalterritory for balloon lumens extending within the coil core (allowingmore lumens and separately inflatable balloons or groups of balloons,and/or allowing larger lumen sizes for faster actuation times) with thesame the axial actuation stroke of the surrounding balloon. Theexemplary cross-sectional shapes include elliptical or othercontinuously curved shapes to facilitate sealing engagement with thesurrounding balloon wall material, with an alternative having proximaland distal regions with circular curvatures corresponding to those ofthe inflated balloon (so as to enhance axially compressive forcetransmission against an axially indented coil spring surface configuredto evenly engage the inflated balloon).

Referring now to FIG. 16, a perspective view of an exemplary introducersheath/input assembly for use in the systems of FIGS. 1 and 8 can beseen in more detail. Introducer/input assembly 460 generally includes anintroducer sheath assembly 462 and an input assembly 464. Introducer 462includes an elongate introducer sheath 466 having a proximal end 468 anda distal end 470 with an axial lumen extending therebetween. A proximalhousing 472 of introducer 462 contains an introducer hemostasis valve.Input 464 includes a flexible joystick shaft 474 having a distal endslidably extending into the lumen of introducer housing 472, and aproximal end affixed to an input housing 476 containing an input valve.A lumen extends axially through input 464, and an articulatable catheter480 can be advanced through both lumens of assembly 460. A cable orother data communication structure of assembly 460 transmits movementcommands from the assembly to a processor of the catheter system so asto induce articulation of the catheter within the patient. Morespecifically, when the catheter system is in a driven articulation mode,and a clutch input 482 of introducer/input assembly 460 is actuated,movement of input housing 476 relative to sheath housing 472 inducesarticulation of one or more articulatable segment of catheter 480 nearthe distal end of the catheter, with the catheter preferably having anyone or more of the articulation structures described herein. The valveswithin the housings of introducer/input assembly may be actuatedindependently to axially affix catheter 480 to introducer 462, and/or toinput 464.

Referring now to FIGS. 17A and 17B, articulation system componentsrelated to those of FIGS. 14A-14C can be seen. Two multi-lumen polymerhelical cores 440 can be interleaved with axially concave helicalsprings along the articulated portion of a catheter. Curved transitionzones extend proximal of the helical cores to axially straightmulti-lumen extensions 540, which may extend along a passive(unarticulated) or differently articulated section of the catheter, orwhich may extend through articulated segments that are driven by fluidtransmitted by other structures (not shown). Advantageously, a portionof each proximal extension 540 near the proximal end can be used as aproximal interface 550 (See FIG. 17C), often by employing an axialseries of lateral ports formed through the outer walls of themulti-lumen shaft into the various lumens of the core. This proximalinterface 550 can be mated with a receptacle 552 of a modular valveassembly 542, or with a receptacle of non-modular valve assembly, orwith a connector or interface body that couples to a manifold so as toprovide sealed, independently controlled fluid communication and acontrolled flow of inflation fluid to desired subsets of the balloonsfrom a pressurized inflation fluid source, along with a controlled flowof exhaust fluid from the balloons to the atmosphere or an exhaust fluidreservoir.

Extensions 540 extend proximally into a valve assembly 542 so as toprovide fluid communication between fluid pathways of the valve assemblyand the balloons of the articulated segment. Valve assembly 542 includesan axial series of modular valve units 542 a, 542 b, 542 c, etc.Endplates and bolts seal fluid paths within the valve assembly and holdthe units in place. Each valve unit of assembly 542 includes at leastone fluid control valve 544, and preferably two or more valves. Thevalves may comprise pressure modulating valves that sense and controlpressure, gate valves, three-way valves (to allow inflation fluid alonga channel to one or more associated balloons, to seal inflation fluid inthe inflation channel and associated balloons while flow from the fluidsource is blocked, and to allow inflation fluid from the channels andballoons to be released), fluid dispersing valves, or the like. O-ringsprovide sealing between the valves and around the extensions 540, andunthreading the bolts may release pressure on the O-rings and allow theextensions to be pulled distally from the valve assembly, therebyproviding a simple quick-disconnect capability. Radial ports 546 areaxially spaced along extensions 540 to provide fluid communicationbetween the valves and associated lumens of the multi-lumen polymerextensions, transitions, and helical coils. Advantageously, where agreater or lesser number of inflation channels will be employed, more orfewer valve units may be axially stacked together. While valves 544 arehere illustrated with external fluid tubing connectors (to be coupled tothe fluid source or the like), the fluid paths to the valves mayalternatively also be included within the modular valve units, forexample, with the fluid supply being transmitted to each of the valvesalong a header lumen that extends axially along the assembly and that issealed between the valve units using additional O-rings or the like.Note that while modular units 542 a, 542 b, . . . may comprise valves,in alternative embodiments these units may simply comprise ferrules,posts, or other interface structures that allow the assembly to be usedas a connector or interface body that helps provide fluid communicationbetween the multi-lumen shaft or core and some of the components of thefluid supply system.

Referring now to FIG. 17C, additional modular valve units 542 d, 542 e,and 542 f are included in the valve and manifold assembly 542′ so asfacilitate independent control of inflation fluid flows to and fromlumens of the multi-lumen cores. The modular valve units are preferablyinterchangeable, and will often include electrical circuitry and apressure sensor for each inflation lumen, along with the valves, platestructures, and channels. The electrical circuitry for each plate willoften be supported by a flex circuit substrate and may optionally beadhesively bonded to one of the major surfaces of the plates, or it maybe between layers of the plate or held compressively between plates.Along with conductive traces for communication between the valves,sensors, and system processor, the flex circuit may also supportelectronics to facilitate multiplexing among the plate modules,plug-and-play plate module capabilities, daisy chaining or networking ofthe plate modules, and/or the like. In exemplary embodiments describedbelow, the flex circuits substrate may also support (and help provideelectrical coupling with MEMS valves and/or MEMS pressure sensors. Theflex circuit substrate or another film substrate material may optionallyhelp support O-rings, gaskets, or other seal materials surroundingpassages through the plates (or layers thereof), including passages thatform receptacles 552, inflation headers, deflation headers, and thelike; though some or all of the seals for these structures may insteadbe independently positioned. As noted above, one or morequick-disconnect fitting 554 may be configured to help seal the ports ofthe multi-lumen shaft (or of an intermediate body) to the fluid channelsof the plates. Where the ports are included on a shaft that extendsthrough the plates, the quick-disconnect fitting may take the form of acompression member that is manually movable between a detachableconfiguration (in which little or no compression is applied betweenplates) and a sealed configuration (in which sufficient compression isapplied between plates to squeeze seal material from between the platesof the stack and against the shafts). The quick-disconnect fitting maycomprise one or more over-center latch, one or more threaded connector,one or more cam unit, or the like.

Referring now to FIG. 18, a simplified manifold schematic shows fluidsupply and control components of an alternative manifold 602. Asgenerally described above, manifold 602 has a plurality of modularmanifold units or valve assembly plates 604 i, 604 ii, . . . stacked inan array. The stack of valve plates are sandwiched between a front endcap 606 and a back end-cap 608, and during use the proximal portion ofthe multi-lumen conduit core(s) extend through apertures in the frontcap and valve plates so that the proximal end of the core is adjacent toor in the back cap, with the apertures defining a multi-lumen corereceptacle. The number of manifold units or modules in the stack issufficient to include a plate module for each lumen of each of themulti-lumen core(s). For example, where an articulatable structure has 3multi-lumen core shafts and each shaft has 6 lumens, the manifoldassembly may include a stack of 6 plates. Each plate optionally includesan inflation valve and a deflation valve to control pressure in one ofthe lumens (and the balloons that are in communication with that lumen)for each multi-lumen shaft. In our 3-multi-lumen shaft/6 lumen eachexample, each plate may include 3 inflation valves (one for a particularlumen of each shaft) and 3 deflation valves (one for that same lumen ofeach shaft). As can be understood with reference to the multi-lumenshaft shown in receptacle 1 of FIG. 18, the spacing between the portsalong the shaft corresponds to the spacing between the fluid channelsalong the receptacle. By inserting the core shaft fully into themulti-lumen shaft receptacle, the plate channel locations can beregistered axially with the core, and with the ports that were drilledradially from the outer surface of the multi-lumen core. The processorcan map the axial locations of the valves along the receptacle with theaxial locations of the ports along the core shafts, so that a port intoa particular lumen of the core can be registered and associated with afluid channel of specific inflation and deflation valves. One or moreinflation headers can be defined by passages axially through thevalve-unit plates; a similar deflation header (not shown) can also beprovided to monitor pressure and quantity of fluid released from thelumen system of the articulated device. O-rings can be provided adjacentthe interface between the plates surrounding the headers andreceptacles. Pressure sensors (not shown) can monitor pressure at theinterface between each plate and the multi-lumen receptacle.

Along with monitoring and controlling inflation and deflation of all theballoons, manifold 602 can also include a vacuum monitor system 610 toverify that no inflation fluid is leaking from the articulated systemwithin the patient body. A simple vacuum pump (such as a syringe pumpwith a latch or the like) can apply a vacuum to an internal volume orchamber of the articulated body surrounding the balloon array.Alternative vacuum sources might include a standard operating roomvacuum supply or more sophisticated powered vacuum pumps. Regardless, ifthe seal of the vacuum chamber degrades the pressure in the chamber ofthe articulated structure will increase. In response to a signal from apressure sensor coupled to the chamber, a shut-off valve canautomatically halt the flow of gas from the canister, close all ballooninflation valves, and/or open all balloon deflation valves. Such avacuum system may provide worthwhile safety advantages when thearticulated structure is to be used within a patient body and theballoons are to be inflated with a fluid that may initially take theform of a liquid but may vaporize to a gas. A lumen of a multi-lumencore shaft may be used to couple a pressure sensor of the manifold to avacuum chamber of the articulated structure via a port of the proximalinterface and an associated channel of the manifold assembly, with thevacuum lumen optionally comprising a central lumen of the multi-lumenshaft and the vacuum port being on or near the proximal end of themulti-lumen shaft.

Referring now to FIGS. 18A-18C, an exemplary alternative modularmanifold assembly 556 has fluid supply and deflation exhaust channelsthat are internal to a stack of plate modules 558. Plate modules 558 arestacked between a front end cap and a back end cap, with the front endcap being at the distal end and having passages or apertures forreceiving each of the multi-lumen shafts, and the back end being at theproximal end and having a socket for receiving a canister 560 of N2O. Asseen most clearly in FIG. 18B, each plate module 558 includes a plate562 formed using multiple plate layers 562 a, 562 b, 562 c . . . . Whilethe plate layers shown here extend across the stack, other layers may bestacked axially along the stack. Regardless, each plate 562 has opposedproximal and distal major surfaces 562 i, 562 ii. A series of passagesextend through the plate between the major surfaces, including one ormore inflation fluid passage 564, one or more receptacle passages 566,and one or more deflation fluid passages 568. When the plates and endcaps are assembled within manifold assembly 556, these passages combineto form one or more inflation header 564′, one or more receptacle 566′,and one or more deflation header 568′, with each of the passagesproviding surfaces that serve as a portion of the assembled structure.Channels 570 extend within plates 562 between the headers 564, 568 andthe receptacle, with inflation valves disposed along the channelsbetween the inflation header 564 and receptacle 566 and deflation valvesdisposed along the channels between the receptacles and the deflationheaders 568. Note that the manifold assembly of FIGS. 18A-18C includesmulti-coil three way valves 572 that function as both inflation valvesand deflation valves, with two three way valves for two multi-lumen coreshafts.

Referring now to FIGS. 18C and 18D, additional optional components ofthe manifold assembly can be understood. The functionality of one, some,or all of these components may be included in any of the manifoldassembly embodiments described herein. Back end cap 574 here includes asystem fluid supply valve 576 disposed along channels coupling theinflation fluid canister 560 with the inflation header 564. Note thatthe end cap may include one or more cross headers to allow separateinflation or exhaust headers for the different multi-lumen core shafts.The system supply valve may halt or allow all of the fluid flow to theremaining components of the manifold and articulation structure. In someembodiments, fluid from canister 560 is used to pressurize a supplyplenum, with a pressure sensor and the system supply valve being used tocontrol the supply plenum pressure. This may be beneficial if it isdesired to use a non-volatile balloon inflation liquid such as saline orthe like, and/or if it is desired to preclude inflation of the balloonsabove a pressure that is below that of canister 560. However,transmitting inflation fluid directly from canister 560 to the inflationvalves of the modular plates may present advantages, including enhancedinflation fluid flows through the small channels of the manifold andarticulated structure when transmitting liquid or a liquid/gas mixtureusing the full canister pressure, as well as the relatively constantpressure that can be provided by vaporization of liquid within thecanister. To keep the gas/liquid inflation fluid pressure within thecanister even more constant, a resistive heater may be thermally coupledwith the outer surface of the canister so as to compensate for theenthalpy of vaporization that occurs therein.

Referring still to FIGS. 18C and 18D, there may be more significantadvantages to having an exhaust plenum 578 between one, some or all ofthe exhaust channels (often between the one or more exhaust header 568)and an exhaust port 580 to atmosphere. A pressure sensor or flow sensorcoupled with exhaust plenum 578 can be used to monitor exhaust fluidflow. In some embodiments, a pressure sensor coupled to exhaust plenum578 and an exhaust valve along a channel coupling the exhaust plenum tothe exhaust port 580 can be used as a back-pressure control system tohelp control exhaust flows, to provide a uniform pressure to a number ofballoons (via the deflation valves), or and/or to calibrate theindividual pressure sensors of the plate modules. Manual release valvesmay optionally be included between the inflation and deflation headersand the surrounding environment to allow the system to be fullydepressurized in case of failure of a valve or the like.

Referring now to FIG. 18E, a simplified pressure control schematicillustrates some of the components of a pressure control system as usedto control the pressure in a single channel of a single plate module (aswell as in an associated balloon or balloons coupled with the channelvia a port of a multi-lumen shaft sealed in fluid communication with thechannel. Pressure control of all the channels may be maintained by thesystem controller 582, with the desired pressures typically beingdetermined by the controller in response to a movement or stiffnesscommand input by the user via a user interface 584. A pressuredifference or error signal for a particular channel is determined from adifference between a sensed pressure (as determined using a pressuresensor 586) and the desired pressure for that channel. In response tothe error signal, controller 582 transmits commands to an inflationvalve 588 and/or a deflation valve 589 so as to raise or lower thepressure in the channel. Though the same fluid is flowing to and fromthe balloons, there may be significant differences between the flowsfrom the canister through inflation valve 588 (which may compriseliquid, often being primarily liquid or even substantially entirelyliquid) and the flows from the balloons through deflation valve 589(which may comprise gas, often being primarily gas or even substantiallyentirely gas). To provide accurate inflation and deflation flow control,there may be advantages to including an inflation orifice between theinflation valve and the receptacle (ideally so as to inhibitvaporization prior to the inflation valve), and/or to including adeflation orifice between the receptacle and the deflation header 568.Such orifices may facilitate accurate flow control despite the use ofsimilar valve structures for use as inflation valve 588 and deflationvalve 589. There may, however, be beneficial differences between theinflation and deflation valves, including the use of normally closedvalves for inflation and normally open valves for deflation (so theballoons will deflate if there is a power failure). Additionally,inflation valve 588 may have a smaller throat and/or a fast response tocontrollably transmit small volumes of liquid (optionally 50 nl or less,often 25 nl or less, and preferably 15 nl or less, and ideally 10 nl orless to provide desirably small movement increments); while deflationvalve 589 will allow gas flows of at least 0.1 scc/s, preferably beingat least 0.5 scc/s or even 1 scc/s or more (to provide desirably fastarticulation response). Hence, the throat sizes of these two valves maybe different in some embodiments. Note that in some embodiments(particularly those with a pressure-controlled plenum between a canisterand the inflation valves, or those having non-cryogenic pressurizedfluid sources), the fluids flowing to and from may be more similar, forexample, with liquid flowing to and from the balloons, gas flowing toand from the balloons, or the like.

Referring to FIGS. 18F and 18G, it may be desirable to use a manifoldassembly (or components thereof) with a number of different types ofarticulatable structures, for example with catheters having differentsizes and/or shapes of multi-lumen shafts. Toward that end, it may bebeneficial to include an interface body 590 for coupling a multi-lumencore shaft 592 (or other lumen-contain substrate) of the articulatablestructure with a receptacle 566 of a manifold assembly 556. Interfacebody 590 has a proximal end and a distal end with an axial lumenextending therebetween. The axial lumen receives a multi-lumen shaftproximally, and the shaft may extend entirely through the interface body(so that registration between the ports of the shaft and the channels ofthe plate modules relies on engagement of the shaft with a surface ofthe back cap as shown in FIG. 18G, the receptacle comprising a blindhole) or the proximal end of the shaft may engage a bottom of the lumenin the interface body (so that the interface body is registered with thereceptacle and the lumen is registered with the interface body). A quickdisconnect fitting 592 is near the distal end of the interface body.Interface body 590 comprises a set of relatively rigid annularstructures or rings 594 (optionally comprising metal or a relativelyhigh-durometer polymer) interleaved with elastomeric seal material 596(optionally overmolded on the rings or the like). Indentationsoptionally run circumferentially around the inner and outer surfaces inthe middle of each ring, and one or more gas passages run radiallybetween an inner surface of the ring and an outer surface of the ring,optionally between the indentations. Features may be included on theaxial ends of the rings to inhibit separation of the body into axialsegments.

Referring still to FIGS. 18F and 18G, the receptacle of the manifold mayoptionally comprise a smooth blind hole that extends through all valveplates of the stack. The valve plates may have fluid channels runninginto and out of the receptacle between the plate/plate borders. Afeature of the manifold will often facilitate coupling, here being ashort threaded tube that extends distally from the manifold around theopening of the receptacle. This feature mates with quick-disconnectfitting 592, shown as a wing-nut to affix the interface body and themulti-lumen shaft to the manifold. To connect the catheter to themanifold, the user inserts the multi-lumen shaft into the interfacebody, slides them both together into the receptacle of the manifold tillthe proximal end of the shaft hits the bottom of the receptacle (or tillthe interface body engages a registration feature). The user can engageand tightens the threads which axially compresses the connector shaft,causing the elastomeric seal material 596 to bulge inward (to sealaround the multi-lumen shaft) and outward (to seal around the interfacebody), separating the receptacle into an axial series of sealed zones,one for each plate. Different interface bodies having different innerdiameters and/or different inner cross-sections can be made fordifferent shaft sizes and shapes. A single thread, fastener, or latchmay optionally apply axial pressure to seal around a plurality ofmulti-lumen shafts, or separate quick-disconnect fittings may beincluded for each shaft.

Referring now to FIG. 19, a further alternative manifold structure 620includes a stack of valve unit plates 622 in which each valve unit isformed with three layers 624, 626, 628. All the layers include axialpassages, and these passages are aligned along the axis of the insertedmulti-lumen core shafts to define multi-lumen receptacles, inflationheaders, deflation headers, and the like. First layer 624 includes valvereceptacles containing discrete microelectromechanical system (MEMS)valves, which may be electrically coupled to the processor and/ormounted to the plate layer using a flex circuit adhesively bonded to theback side of the layer (not shown), with the flex circuit optionallyhaving O-rings mounted or formed thereon to seal between adjacent valveunit plates. Second valve layer 626 may have through-holes coupled bychannels to provide flow between the valve ports, headers, andmulti-lumen receptacles, and may be sealingly bonded between third platelayer 628 and first plate layer 624 (optionally with O-rings engagingthe valves around the valve ports. Suitable MEMS valves may be availablefrom DunAn Microstaq, Inc., of Texas, NanoSpace of Sweeden, Moog ofCalifornia, or others. The assembled modular valve-unit stack may havedimensions of less than 2½″×2½″×2″ for a two or three multi-lumen coresystem having 12 lumens per core (and thus including 36 separatelycontrollable lumen channels, and having an inflation valve and adeflation valve for each lumen for a total of at least 64 valves). Platelayers 624, 626, 628 may comprise polymers (particularly polymers whichare suitable for use at low temperatures (such as PTFE, FEP, PCTFE, orthe like), metal (such as aluminum, stainless steel, brass, alloys, anamorphous metal alloy such as a Liquidmetal™ alloy, or the like), glass,semiconductor materials, or the like, and may be mechanically machinedor laser-micromachined, 3D printed, or patterned usingstereolithography, but will preferable be molded. Alternative MEMS valvesystems may have the valve structure integrated into the channel platestructure, further reducing size and weight.

Referring to FIGS. 19A and 19B, additional features that can be includedin the plate layer structure of MEMS manifold 620 can be understood.Many of the channels, passages, and features shown here are forinterfacing with a single multi-lumen shaft for simplicity; additionalfeatures may be included for additional shafts. As control over thefluid channels may benefit from pressure sensors coupled with thechannels of each plate module, an aperture for a MEMS pressure sensor625 is included in first plate 624, with an associated channel 627(extending between the receptacle and a pressure sensing region of thepressure sensor) being included in second plate 626. Suitable pressuresensors may be commercially available from Merit Sensor Systems and anumber of alternative suppliers. As the pressure sensor and the valvemay have different thicknesses, it may be beneficial to separate firstlayer 624 into two layers (with the aperture for the thicker componentsprovided in both, and the aperture for the thinner component only beingprovided through one). As the pressure sensor may benefit from anexternal reference pressure, a relief channel may be formed in thirdplate 628 extending from a reference pressure location on the sensor toan external port. As can be understood with reference to FIG. 19B, thelayers combine to form a plate structure 562″, with each plate havingopposed proximal and distal major surfaces. The plates (and thecomponents supported thereon to make up the plate modules) can bestacked to form the modular manifold array.

Many of the flexible articulated devices described above rely oninflation of one or more balloons to articulate a structure from a firstresting state to a second state in which a skeleton of the flexiblestructure is resiliently stressed. By deflating the balloons, theskeleton can urge the flexible structure back toward the originalresting state. This simple system may have advantages for manyapplications. Nonetheless, there may be advantages to alternativesystems in which a first actuator or set of actuators urges a flexiblestructure from a first state (for example, a straight configuration) toa second state (for example, a bent or elongate configuration), and inwhich a second actuator or set of actuators are mounted in opposition tothe first set such that the second can actively and controllably urgethe flexible structure from the second state back to the first state.Toward that end, exemplary systems described below often use a first setof balloons to locally axially elongate a structural skeleton, and asecond set of balloons mounted to the skeleton to locally axiallycontract the structural skeleton. Note that the skeletons of suchopposed balloon systems may have very little lateral or axial stiffness(within their range of motion) when no balloons are inflated.

Referring now to FIGS. 20A and 20B, a simplified exemplary C-channelstructural skeleton 630 (or portion or cross section of a skeleton) isshown in an axially extended configuration (in FIG. 19), and in anaxially contracted configuration (in FIG. 20). C-frame skeleton 630includes an axial series of C-channel members or frames 632 extendingbetween a proximal end 634 and a distal end 636, with each rigidC-channel including an axial wall 638, a proximal flange 640, and adistal flange 642 (generically referenced as flanges 640). The opposedmajor surfaces of the walls 644, 646 are oriented laterally, and theopposed major surfaces of the flanges 648, 650 are oriented axially (andmore specifically distally and proximally, respectively. The C-channelsalternate in orientation so that the frames are interlocked by theflanges. Hence, axially adjacent frames overlap, with the proximal anddistal surfaces 650, 648 of two adjacent frames defining an overlapoffset 652. The flanges also define additional offsets 654, with theseoffsets being measured between flanges of adjacent similarly orientedframes.

In the schematics of FIGS. 19 and 20, three balloons are disposed in thechannels of each C-frame 632. Although the balloons themselves may (ormay not) be structurally similar, the balloons are of two differentfunctional types: extension balloons 660 and contraction balloons 662.Both types of balloons are disposed axially between a proximallyoriented surface of a flange that is just distal of the balloon, and adistally oriented surface of a flange that is just proximal of theballoon. However, contraction balloons 662 are also sandwiched laterallybetween a first wall 638 of a first adjacent C-channel 632 and a secondwall of a second adjacent channel. In contrast, extension balloons 660have only a single wall on one lateral side; the opposite sides ofextension balloons 660 are not covered by the frame (though they willtypically be disposed within a flexible sheath or other components ofthe overall catheter system).

A comparison of C-frame skeleton 630 in the elongate configuration ofFIG. 19 to the skeleton in the short configuration of FIG. 20illustrates how selective inflation and deflation of the balloons can beused to induce axial extension and contraction. Note that the C-frames632 are shown laterally reversed from each other in these schematics. InFIG. 19, extension balloons 660 are being fully inflated, pushing theadjacent flange surfaces apart so as to increase the axial separationbetween the associated frames. As two contraction balloons 662 aredisposed in each C-channel with a single extension balloon, and as thesize of the channel will not significantly increase, the contractionballoons will often be allowed to deflate at least somewhat withexpansion of the extension balloons. Hence, offsets 654 will be urged toexpand, and contraction offsets 652 will be allowed to decrease. Incontrast, when skeleton 630 is to be driven toward the axiallycontracted configuration of FIG. 20, the contraction balloons 662 areinflated, thereby pushing the flanges of the overlapping frames axiallyapart to force contraction overlap 652 to increase and axially pull thelocal skeleton structure into a shorter configuration. To allow the twocontraction balloons 662 to expand within a particular C-channel, theexpansion balloons 660 can be allowed to deflate.

While the overall difference between C-frame skeleton 630 in thecontracted configuration and in the extended configuration issignificant (and such skeletons may find advantageous uses), it isworthwhile noting that the presence of one extension balloon and twocontraction balloons in a single C-channel may present disadvantages ascompared to other extension/contraction frame arrangements describedherein. In particular, the use of three balloons in one channel canlimit the total stroke or axial change in the associated offset thatsome of the balloons may be able to impose. Even if similar balloon/coreassemblies are used as extension and contraction balloons in athree-balloon wide C-channel, the two contraction balloons may only beused for about half of the stroke of the single extension balloon, asthe single extension stroke in the channel may not accommodate two fullcontractions strokes. Moreover, there are advantages to limiting thenumber of balloon/core assemblies used in a single articulated segment.

Note that whichever extension/contraction skeleton configuration isselected, the axial change in length of the skeleton that is inducedwhen a particular subset of balloons are inflated and deflated willoften be local, optionally both axially local (for example, so as tochange a length along a desired articulated segment without changinglengths of other axial segments) and—where the frames extend laterallyand/or circumferentially—laterally local (for example, so as to impose alateral bend by extending one lateral side of the skeleton withoutchanging an axial length of the other lateral side of the skeleton).Note also that use of the balloons in opposition will often involvecoordinated inflating and deflating of opposed balloons to provide amaximum change in length of the skeleton. There are significantadvantages to this arrangement, however, in that the ability toindependently control the pressure on the balloons positioned on eitherside of a flange (so as to constrain an axial position of that flange)allows the shape and the position or pose of the skeleton to bemodulated. If both balloons are inflated evenly at with relatively lowpressures (for example, at less that 10% of full inflation pressures),the flange may be urged to a middle position between the balloons, butcan move resiliently with light environmental forces by compressing thegas in the balloons, mimicking a low-spring force system. If bothballoons are evenly inflated but with higher pressures, the skeleton mayhave the same nominal or resting pose, but may then resist deformationfrom that nominal pose with a greater stiffness.

An alternative S-channel skeleton 670 is shown schematically incontracted and extended configurations in FIGS. 21A and 21B,respectively, which may have both an improved stroke efficiency (givinga greater percent change in axial skeleton length for an availableballoon stroke) and have fewer components than skeleton 632. S-skeleton670 has many of the components and interactions described aboveregarding C-frame skeleton 630, but is here formed of structuralS-channel members or frames 672. Each S-channel frame 672 has two walls644 and three flanges 640, the proximal wall of the frame having adistal flange that is integral with the proximal flange of the distalwall of that frame. Axially adjacent S-channels are again interlocked,and in this embodiment, each side of the S-channel frame has a channelthat receives one extension balloon 660 and one contraction balloon 662.This allows all extension balloons and all contraction balloons to takefull advantage of a common stroke. Moreover, while there are twoextension balloons for each contraction balloon, every other extensionballoon may optionally be omitted without altering the basicextension/contraction functionality (though the forces available forextension may be reduced). In other words, if the extension balloons660′ as marked with an X were omitted, the skeleton could remain fullyconstrained throughout the same nominal range of motion. Hence,S-channel frame 672 may optionally use three or just two sets of opposedballoons for a particular articulation segment.

Referring now to FIG. 22A, a modified C-frame skeleton 680 hascomponents that share aspects of both C-frame skeleton 630 and S-frameskeleton 670, and may offer advantages over both in at least someembodiments. Modified C skeleton 680 has two different generallyC-frames or members: a C-frame 682, and a bumper C-frame 684. C-frame682 and bumper frame 64 both have channels defined by walls 644 andflanges 648 with an axial width to accommodate two balloon assemblies,similar to the channels of the S-frames 672. Bumper frame 684 also has aprotrusion or nub 686 that extends from one flange axially into thechannel. The adjacent axial surfaces of these different frame shapesengage each other at the nub 686, allowing the frames to pivot relativeto each other and facilitating axial bending of the overall skeleton,particularly when using helical frame members.

Referring now to FIGS. 22B and 22C, a relationship between the schematicextension/retraction frame illustration of FIGS. 20A-22A and a firstexemplary three dimensional skeleton geometry can be understood. To forman axisymmetric ring-frame skeleton structure 690 from the schematicmodified C-frame skeleton 680 of FIG. 22B, the geometry of frame members682, 684 can be rotated about an axis 688, resulting in annular or ringframes 692, 694. These ring frames retain the wall and flange geometrydescribed above, but now with annular wall and flanges beinginterlocked. The annular C-frames 682, 684 were facing differentdirections in schematic skeleton 680, so that outer C-frame ring 692 hasan outer wall (sometimes being referred to as outer ring frame 692) anda channel that opens radially inwardly, while bumper C-frame ring 694has a channel that is open radially outwardly and an inner wall (so thatthis frame is sometimes referred to as the inner ring frame 694). Ringnub 696 remains on inner ring frame 694, but could alternatively beformed on the adjacent surface of the outer ring frame (or usingcorresponding features on both). Note that nub 696 may add more valuewhere the frame deforms with bending (for example, the frame deformationwith articulation of the helical frame structures described below) asthe deformation may involve twisting that causes differential angels ofthe adjacent flange faces. Hence, a non-deforming ring frame structuremight optionally omit the nub in some implementations.

Referring now to FIGS. 22C-22F, uniform axial extension and contractionof a segment of ring-frame skeleton 690 is performed largely asdescribed above. To push uniformly about the axis of the ring frames,three balloons are distributed evenly about the axis between the flanges(with centers separated by 120 degrees). The balloons are shown here asspheres for simplicity, and are again separated into extension balloons660 and contraction balloons 662. In the straight extended configurationof FIG. 22D, the extension balloons 660 of the segment are all fullyinflated, while the contraction balloons 662 are all fully deflated. Inan intermediate length configuration shown in FIG. 22E, both sets ofballoons 660, 662 are in an intermediate inflation configuration. In theshort configuration of FIG. 22F, contraction balloons 662 are all fullyinflated, while extension balloons 660 are deflated. Note that the stateof the balloons remains axisymmetrical, so that the lengths on alllateral sides of the ring frame skeleton 690 remain consistent and theaxis of the skeleton remains straight.

As can be understood with reference to FIGS. 22G and 22H, lateralbending or deflection of the axis of ring-frame skeleton 690 can beaccomplished by differential lateral inflation of subsets of theextension and contraction balloons. There are three balloons distributedabout the axis between each pair of articulated flanges, so that theextension balloons 660 are divided into three sets 660 i, 660 ii, and660 iii. Similarly, there are three sets of contraction balloons 662 i,662 ii, and 662 iii. The balloons of each set are aligned along the samelateral orientation from the axis. In some exemplary embodiments, eachset of extension balloons (extension balloons 660 i, extension balloons660 ii, and extension balloons 660 iii) along a particular segment iscoupled to an associated inflation fluid channel (for example, a channeli for extension balloons 660 i, a channel ii for extension balloons 660ii, and a channel iii for extension balloons 660 iii, the channels notshown here). Similarly, each set of contraction balloons 662 i, 662 ii,and 662 iii is coupled to an associated inflation channel (for example,channels iv, v, and vi, respectively) so that there are a total of 6lumens or channels per segment (providing three degrees of freedom andthree orientation-related stiffnesses). Other segments may have separatefluid channels to provide separate degrees of freedom, and alternativesegments may have fewer than 6 fluid channels. Regardless, byselectively deflating the extension balloons of a first lateralorientation 660 i and inflating the opposed contraction balloons 662 i,a first side of ring frame skeleton 690 can be shortened. By selectivelyinflating the extension balloons of the other orientations 660 ii, 660iii, and by selectively deflating the contraction balloons of thoseother orientations 662 ii, 662 iii, the laterally opposed portion ofring frame skeleton 690 can be locally extended, causing the axis of theskeleton to bend. By modulating the amount of elongation and contractiondistributed about the three opposed extension/contraction balloonorientations, the skeleton pose can be smoothly and continuously movedand controlled in three degrees of freedom.

Referring now to FIGS. 23A and 23B, as described above with reference toFIGS. 21A and 21B, while it is possible to include balloons between allthe separated flanges so as to maximize available extension forces andthe like, there may be advantages to foregoing kinematically redundantballoons in the system for compactness, simplicity, and cost. Towardthat end, ring frame skeletons having 1-for-1 opposed extension andcontraction balloons (660 i, 660 ii, and 660 iii; and 662 i, 662 ii, and662 iii) can provide the same degrees of freedom and range of motion asprovided by the segments of FIGS. 22G and 22H (including two transverseX-Y lateral bending degrees of freedom and an axial Z degree offreedom), and can also control stiffness, optionally differentiallymodulating stiffness of the skeleton in different orientations in 3Dspace. The total degrees of freedom of such a segment may appropriatelybe referenced as being 4-D (X, Y, Z, & S for Stiffness), with thestiffness degree of freedom optionally having 3 orientational components(so as to provide as many as 5-D or 6-D. Regardless, the 6 fluidchannels may be used to control 4 degrees of freedom of the segment.

As can be understood with reference to FIGS. 23C-23E and 23H, elongateflexible bodies having ring-frame skeletons 690′ with larger numbers ofinner and outer ring frames 692, 694 (along with associated largernumbers of extension and retraction balloons) will often provide agreater range of motion than those having fewer ring frames. Theelongation or Z axis range of motion that can be provided by balloonarticulation array may be expressed as a percentage of the overalllength of the structure, with larger percentage elongations providinggreater ranges of motion. The local changes in axial length that aballoon array may be able to produce along a segment having ring frames690, 690′ (or more generally having the extension contraction skeletonsystems described herein) may be in a range of from about 1 percent toabout 45 percent, typically being from about 2½ percent to about 25percent, more typically being from about 5 percent to about 20 percent,and in many cases being from about 7½ percent to about 17½ percent ofthe overall length of the skeleton. Hence, the longer axial segmentlength of ring frame skeleton 690′ will provide a greater axial range ofmotion between a contracted configuration (as shown in FIG. 23E) and anextended configuration (as shown in FIG. 23C), while still allowingcontrol throughout a range of intermediate axial length states (as shownin FIG. 23D).

As can be understood with reference to FIGS. 23A, 23B, 23D and 23H,setting the balloon pressures so as to axially contract one side of aring frame skeleton 690′ (having a relatively larger number of ringframes) and axially extend the other side laterally bends or deflectsthe axis of the skeleton through a considerable angle (as compared to aring frame skeleton having fewer ring frames), with each frame/frameinterface typically between 1 and 15 degrees of axial bend angle, moretypically being from about 2 to about 12 degrees, and often being fromabout 3 to about 8 degrees. A catheter or other articulated elongateflexible body having a ring frame skeleton may be bent with a radius ofcurvature (as measured at the axis of the body) of between 2 and 20times an outer diameter of the skeleton, more typically being from about2.25 to about 15 times, and most often being from about 2.4 to about 8times. While more extension and contraction balloons 660, 662 are usedto provide this range of motion, the extension and contraction balloonsubsets (660 i, 660 ii, and 660 iii; and 662 i, 662 ii, and 662 iii) maystill each be supplied by a single common fluid supply lumen. Forexample, 6 fluid supply channels may each be used to inflate and deflate16 balloons in the embodiment shown, with the balloons on a single lumenbeing extension balloons 660 i aligned along one lateral orientation.

As can be understood with reference to ring frame skeleton 690′ in thestraight configuration of FIG. 23D, in the continuously bentconfiguration of FIG. 23H, and in the combined straight and bentconfiguration of FIG. 23F, exemplary embodiments of the elongateskeleton 690′ and actuation array balloon structures described hereinmay be functionally separated into a plurality of axial segments 690 i,690 ii. Note that many or most of the skeleton components (includingframe members or axial series of frame members, and the like) andactuation array components (including the substrate and/or core, some orall of the fluid channels, the balloon outer tube or sheath material,and the like), along with many of the other structures of the elongateflexible body (such as the inner and outer sheaths, electricalconductors and/or optical conduits for diagnostic, therapeutic, sensing,navigation, valve control, and other functions) may extend continuouslyalong two or more axial segments with few or no differences betweenadjacent segments, and optionally without any separation in thefunctional capabilities between adjacent segments. For example, anarticulated body having a two-segment ring frame skeleton 690′ system asshown in FIG. 23H may have a continuous axial series of inner and outerring frames 692, 694 that extends across the interface between thejoints such that the two segments can be bent in coordination with aconstant bend radius by directing similar inflation fluid quantities andpressures along the fluid supply channels associated with the twoseparate segments. As can be understood with reference to FIG. 23G,other than differing articulation states of the segments, there mayoptionally be few or no visible indications of where one segment endsand another begins.

Despite having many shared components (and a very simple and relativelycontinuous overall structure), functionally separating an elongateskeleton into segments provides tremendous flexibility and adaptabilityto the overall articulation system. Similar bend radii may optionally beprovided with differing stiffnesses by applying appropriately differingpressures to the opposed balloons 660, 662 of two (or more) segments 690i, 690 ii. Moreover, as can be understood with reference to FIG. 23F,two (or more) different desired bend radii, and/or two different lateralbend orientations and/or two different axial segments lengths can beprovided by applying differing inflation fluid supply pressures to theopposed contraction/extension balloon sets 660 i, 660 ii, 660 iii, 662i, 662 ii, 662 iii of the segments. Note that the work spaces ofsingle-segment and two-segment systems may overlap so that both types ofsystems may be able to place an end effector or tool at a desiredposition in 3D space (or even throughout a desired range of locations),but multiple-segment systems will often be able to achieve additionaldegrees of freedom, such as allowing the end effector or tool to beoriented in one or more rotational degrees of freedom in 6D space. Asshown in FIG. 23J, articulated systems having more than two segmentsoffer still more flexibility, with this embodiment of ring frameskeleton 690′ having 4 functional segments 690 a, 690 b, 690 c, and 690d. Note that still further design alternatives may be used to increasefunctionality and cost/complexity of the system for a desired workspace,such as having segments of differing length (such as providing arelatively short distal segment 690 a supported by a longer segmenthaving the combined lengths of 690 b, 690 c, and 690 d. While many ofthe multi-segment embodiments have been shown and described withreference to planar configurations of the segments where all thesegments lie in a single plane and are either straight or in a fullybent configuration, it should also be fully understood that theplurality of segments 690 i, 690 ii, etc., may bend along differingplanes and with differing bend radii, differing axial elongation states,and/or differing stiffness states, as can be understood with referenceto FIG. 23I.

Catheters and other elongate flexible articulated structures having ringframe skeletons as described above with reference to FIGS. 22C-23Iprovide tremendous advantages in flexibility and simplicity over knownarticulation systems, particularly for providing large numbers ofdegrees of freedom and when coupled with any of the fluid supply systemsdescribed herein. Suitable ring frames may be formed of polymers (suchas nylons, urethanes, PEBAX, PEEK, HDPE, UHDPE, or the like) or metals(such as aluminum, stainless steel, brass, silver, alloys, or the like),optionally using 3D printing, injection molding, laser welding, adhesivebonding, or the like. Articulation balloon substrate structures mayinitially be fabricated and the balloon arrays assembled with thesubstrates in a planar configuration as described above, with the arraysthen being assembled with and/or mounted on the skeletons, optionallywith the substrates being adhesively bonded to the radially innersurfaces of the inner rings and/or to the radially outer surfaces of theouter rings, and with helical or serpentine axial sections of thesubstrate bridging between ring frames. While extension and retractionballoons 660, 662 associated with the ring frame embodiments are shownas spherical herein, using circumferentially elongate (and optionallybent) balloons may increase an area of the balloon/skeleton interface,and thereby enhance axial contraction and extension forces. A hugevariety of modifications might also be made to the general ring-frameskeletal arrangement and the associated balloon arrays. For example,rather than circumferentially separating the balloons into three lateralorientations, alternative embodiments may have four lateral orientations(+X, −X, +Y, and −Y) so that four sets of contraction balloons aremounted to the frame in opposition to four sets of extension balloons.Regardless, while ring-frame skeletons have lots of capability andflexibility and are relatively geometrically simple so that theirfunctionality is relatively easy to understand, alternativeextension/contraction articulation systems having helical skeletonmembers (as described below) may be more easily fabricated and/or moreeasily assembled with articulation balloon array components,particularly when using the advantageous helical multi-lumen coresubstrates and continuous balloon tube structures described above.

First reviewing components of an exemplary helical framecontraction/expansion articulation system, FIGS. 24A-24E illustrateactuation balloon array components and their use in a helical balloonassembly. FIGS. 24F and 24G illustrate exemplary outer and inner helicalframe members. After reviewing these components, the structure and useof exemplary helical contraction/expansion articulation systems(sometimes referred to herein as helical push/pull systems) can beunderstood with reference to FIGS. 25 and 26.

Referring now to FIGS. 24A and 24B, an exemplary multi-lumen conduit orballoon assembly core shaft has a structure similar to that of the coredescribed above with reference to FIGS. 14 and 15. Core 702 has aproximal end 704 and a distal end 706 with a multi-lumen body 708extending therebetween. A plurality of lumens 710 a, 710 b, 710 c, . . .extend between the proximal and distal ends. The number of lumensincluded in a single core 702 may vary between 3 and 30, with exemplaryembodiments have 3, 7 (of which one is a central lumen), 10 (including 1central), 13 (including 1 central), 17 (one being central), or the like.The multi-lumen core will often be round but may alternatively have anelliptical or other elongate cross-section as described above. Whenround, core 702 may have a diameter 712 in a range from about 0.010″ toabout 1″, more typically being in a range from about 0.020″ to about0.250″, and ideally being in a range from about 0.025″ to about 0.100″for use in catheters. Each lumen will typically have a diameter 714 in arange from about 0.0005″ to about 0.05″, more preferably having adiameter in a range from about 0.001″ to about 0.020″, and ideallyhaving a diameter in a range from about 0.0015″ to about 0.010″. Thecore shafts will typically comprise extruded polymer such as a nylon,urethane, PEBAX, PEEK, PET, other polymers identified above, or thelike, and the extrusion will often provide a wall thickness surroundingeach lumen of more than about 0.0015″, often being about 0.003″ or more.The exemplary extruded core shown has an OD of about 0.0276″″, and 7lumens of about 0.004″ each, with each lumen surrounded by at least0.004″ of the extruded nylon core material.

Referring still to FIGS. 24A and 24B, the lumens of core 702 may haveradial balloon/lumen ports 716 a, 716 b, 716 c, . . . , with each portcomprising one or more holes formed through the wall of core 702 andinto an associated lumen 710 a, 710 b, 710 c, . . . respectively. Theports are here shown as a group of 5 holes, but may be formed using 1 ormore holes, with the holes typically being round but optionally beingaxially elongate and/or shaped so as to reduce pressure drop of fluidflow therethrough. In other embodiments (and particularly those having aplurality of balloons supplied with inflation fluid by a single lumen),having a significant pressure drop between the lumen and the balloon mayhelp even the inflation state of balloons, so that a total cross sectionof each port may optionally be smaller than a cross-section of the lumen(and/or by limiting the ports to one or two round lumens). Typical portsmay be formed using 1 to 10 holes having diameters that are between 10%of a diameter of the associated lumen and 150% of the diameter of thelumen, often being from 25% to 100%, and in many cases having diametersof between 0.001″ and 0.050″. Where more than one hole is included in aport they will generally be grouped together within a span that isshorter than a length of the balloons, as each port will be containedwithin an associated balloon. Spacing between the ports will correspondto a spacing between balloons to facilitate sealing of each balloon fromthe axially adjacent balloons.

Regarding which lumens open to which ports, the ports along a distalportion of the core shaft will often be formed in sets, with each setbeing configured to provide fluid flow to and from an associated set ofballoons that will be distributed along the loops of the core (once thecore is bent to a helical configuration) for a particular articulatedsegment of the articulated flexible body. When the number of lumens inthe core is sufficient, there will often be separate sets of ports fordifferent segments of the articulated device. The ports of each set willoften form a periodic pattern along the axis of the multi-lumen core702, so that the ports provide fluid communication into M differentlumens (M being the number of different balloon orientations that are tobe distributed about the articulated device axis, often being 3 or 4,i.e., lumen 710 a, lumen 710 b, and lumen 710 c) and the patternrepeating N times (N often being the number of contraction balloonsalong each orientation of a segment). Hence, the multi-lumen coreconduit can function as a substrate that supports the balloons, and thatdefines the balloon array locations and associated fluid supply networksdescribed above. Separate multi-lumen cores 702 and associated balloonarrays may be provided for contraction and expansion balloons.

As one example, a port pattern might be desired that includes a 3×5contraction balloon array for a particular segment of a catheter. Thisset of ports might be suitable when the segment is to have three lateralballoon orientations (M=3) and 5 contraction balloons aligned along eachlateral orientation (N=5). In this example, the distal-most port 716 aof the set may be formed through the outer surface of the core into afirst lumen 710 a, the next proximal port 716 b to lumen 710 b, the nextport 716 c to lumen 710 c, so that the first 3 (M) balloons define an“a, b, c” pattern that will open into the three balloons that willeventually be on the distal-most helical loop of the set. The samepattern may be repeated 5 times (for example: a, b, c, a, b, c, a, b, c,a, b, c, a, b, c) for the 5 loops of the helical coil that will supportall 15 contraction balloons of a segment to the fluid supply system suchthat the 5 contraction balloons along each orientation of the segmentare in fluid communication with a common supply lumen. Where the segmentwill include expansion balloons mounted 1-to-1 in opposition to thecontraction balloons, a separate multi-lumen core and associated balloonmay have a similar port set; where the segment will include 2 expansionballoons mounted in opposition for each contraction balloon, twoseparate multi-lumen cores and may be provided, each having a similarport set.

If the same multi-lumen core supplies fluid to (and supports balloonsof) another independent segment, another set of ports may be providedaxially adjacent to the first pattern, with the ports of the second setbeing formed into an M′×N′ pattern that open into different lumens ofthe helical coil (for example, where M′=3 and N′=5: d, e, f, d, e, f, d,e, f, d, e, f, d, e, f), and so on for any additional segments. Notethat the number of circumferential balloon orientations (M) will oftenbe the same for different segments using a single core, but may bedifferent in some cases. When M differs between different segments ofthe same core, the spacing between ports (and associated balloonsmounted to the core) may also change. The number of axially alignedcontraction balloons may also be different for different segments of thesame helical core, but will often be the same. Note also that all theballoons (and associated fluid lumens) for a particular segment that areon a particular multi-lumen core will typically be either only extensionor only contraction balloons (as the extension and contraction balloonarrays are disposed in helical spaces that may be at least partiallyseparated by the preferred helical frame structures described below). Asingle, simple pattern of ports may be disposed near the proximal end ofcore shaft 702 to interface each lumen with an associated valve plate ofthe manifold, the ports here being sized to minimized pressure drop andthe port-port spacing corresponding to the valve plate thickness.Regardless, the exemplary core shown has distal ports formed usinggroups of 5 holes (each having a diameter of 0.006″, centerline spacingwithin the group being 0.012″), with the groups being separated axiallyby about 0.103″.

Referring still to FIGS. 24A and 24B, an exemplary laser drillingpattern for forming ports appropriate for an articulated two distalsegments, each having a 3×4 balloon array, may be summarized in tableform as shown in Table 1:

TABLE 1 Drill to Lumen #s_\ Theta 1 Theta 2 Theta 3 Segment 1, 1 2 3 N1N2 1 2 3 N3 1 2 3 N4 1 2 3 Segment 2, 4 5 6 N1 N2 4 5 6 N3 4 5 6 N4 4 56Theta 1, Theta 2, and Theta 3 here indicate the three lateral bendingorientations, and as M=3, the balloons will typically have centerlinesseparated by about 120 degrees once the balloon/shaft assembly iscoiled. Hence, the centerline spacing between the ports along thestraight shaft (prior to coiling) will typically correspond to a helicalsegment length having about a 120 degree arc angle of the finalarticulated structure, both within a particular N subset and betweenadjacent N subsets of a segment. However, the alignment of eachcircumferential subset along a lateral bending axis does not necessarilymean that adjacent balloons are separated by precisely 120 degrees, orthat the N balloons of a subset are aligned exactly parallel to the axiswhen the segment is in all configurations. For example, there may besome unwinding of the helical core associated with axial elongation, andthere may be benefits to having the balloons along a particular bendingorientation trending slightly circumferentially around the axis (whengoing from balloon to balloon of a lateral bending subset) so thatlateral bends are closer to being planer in more segment states. Theseparation between balloons may remain consistent between segments, ormay be somewhat longer to accommodate affixation of the balloon/shaftassembly to frames and inner and outer sheaths. Drill patterns for theproximal end may be somewhat simpler, as a single port may be drilled toprovide fluid communication between each lumen and an associated valveplate module of the manifold assembly, as shown in Table 2:

TABLE 2 Drill to Lumen #s Plate 1 1 Plate 2 2 Plate 3 3 Plate 4 4 Plate5 5 Plate 6 6 Plate 7 Plate 8Note that this tabular data provides a correlation between valves of aplate and subsets of articulation balloons, and thus of the kinematicsof the system. Hence, the system processor will often have access tothis or related data when an articulated structure is coupled with themanifold, preferably on a plug-and-play basis. Similar (though possiblydifferent) drill patterns may correlate the drill patterns of othermulti-lumen cores with the valves and kinematics.

Referring now to FIGS. 24C and 24D, a continuous tube of flexibleballoon wall material 718 may be formed by periodically varying adiameter of tube wall material to form a series of balloon shapes 720separated by smaller profile sealing zones 722. Balloon tube 718 mayinclude between about 9 and about 290 regularly spaced balloon shapes720, with the sealing zones typically having an inner diameter that isabout equal to the outer diameters of the multi-lumen helical coreshafts 702 described above. In some embodiments, the inner diameters ofthe sealing zones may be significantly larger than the outer diametersof the associated cores when the balloon tube is formed, and thediameters of the sealing zones may be decreased (such as by heatshrinking or axially pull-forming) before or during assembly of theballoon tube and core shaft. The sealing zone may have a length ofbetween about 0.025″ and about 0.500″, often being between about 0.050″and about 0.250″. Decreasing the length of the sealing zone allows thelength of the balloon to be increased for a given catheter size so as toprovide larger balloon/frame engagement interfaces (and thus greaterarticulation forces), while longer sealing zones may facilitate assemblyand sealing between balloons so as to avoid cross-talk betweenarticulation channels.

Referring still to FIGS. 24C and 24D, the balloon shapes 720 of theballoon tube 718 may have diameters that are larger than the diametersof the sealing zones by between about 10% and about 200%, more typicallybeing larger by an amount in a range from about 20% to about 120%, andoften being from about 40% to about 75%. The thickness of balloon tube718 will often vary axially with the varying local diameter of the tube,the locally large diameter portions forming the balloon shapesoptionally being in a range from about 0.00008′ (or about 2 microns) toabout 0.005″, typically being from about 0.001″ and about 0.003″.Balloon tube 718 may initially be formed with a constant diameter andthickness, and the diameter may be locally expanded (by blow forming, byvacuum forming, by a combination of both blow forming and vacuumforming, or by otherwise processing the tube material along the balloonshapes 720), and/or the diameter of the balloon tube may be locallydecreased (by heat shrinking, by axial pull-forming, by a combination ofboth heat shrinking and pull forming, or by otherwise processing thetube material along the sealing zones), with the tube material oftenbeing processed so as to both locally expand the diameter along thedesired balloon shapes and to locally contract the diameter along thesealing zones. Particularly advantageous techniques for forming balloontubes may include the use of extruded polymer tubing corrugators,including the vertical small bore corrugators commercially availablefrom Unicore, Corma, Fraenkische, and others. Suitable custom molds forsuch pipe corrugators may be commercially available from GlobalMed,Custom Pipe, Fraenkische, and others. Still more advanced fabricationtechniques may allow blow or vacuum corrugation using a robotic shuttlecorrugator and custom molds, particularly when it is desirable to changea size or spacing of balloons along a continuous tube. It should benoted that while a single continuous balloon tube is shown, a pluralityof balloon tubes (each having a plurality (or in some cases, at leastone) balloon shape) can be sealingly mounted onto a single core.Regardless, the sealing zones will often have a material thickness thatis greater than that of the balloon shapes.

The balloon shapes 720 of the balloon tube 718 may each have arelatively simple cylindrical center section prior to assembly as shown.The tapers between the balloon center sections and the sealing zones cantake any of a variety of shapes. The tapers may, for example, be roughlyconical, rounded, or squared, and will preferably be relatively short soas to allow greater balloon/frame engagement for a given landing zonelength. More complex embodiments may also be provided, including formingthe balloon shapes with curved cylindrical center sections, optionallywhile corrugating or undulating the surfaces of the tapers so that theballoon tube overall remains relatively straight. The lengths of eachcenter section is typically sufficient to define an arc-angle of from 5to 180 degrees about the axis of the desired balloon assembly helix,more typically being from about 10 to about 50 degrees, the lengths ofthe center sections often being in a range from about 0.010″ to about0.400″ for medical applications, more typically being from about 0.020″to about 0.150″, and many times being in a range from about 0.025″ toabout 0.100″. The exemplary balloon shapes may have an outer diameter ofabout 0.051″ over a total balloon length (including the tapers) of about0.059″

As can be understood with reference to FIGS. 24C, 24D, 24E, and 24E-1,balloon tube 718 may be sealingly affixed to core 702, and thecore/balloon tube assembly may then be formed into a desired helicalshape. The balloon tube may be sealed over the helical core usingadhesive (such as any of those described above, often including UV-curedadhesives) thermal bonding, laser bonding, die bonding, and/or the like.Sealing of the balloons may also benefit from a compression structuredisposed over the balloon material to help maintain tube/core engagementwhen the balloons are inflated. Suitable compression structures ortechniques may include short sections of heat-shrink materials (such asPET) shrunk onto the sealing zones, high-strength filament windingswrapped circumferentially around the sealing zones and adhesivelybonded, swaging of metallic ring structures similar to marker bands overthe sealing zones, small bore crimp clamps over the sealing zones,heat-shrinking and/or pull forming the balloon tube onto the core, orthe like. Any two or more of these may also be combined, for example,with the balloon tube being adhesively bonded to the core tube byinjecting adhesive into the balloon tube around the sealing zone, heatshrinking the balloon tube and a surrounding PET sleeve over the sealingzone, and then swaging a metallic marker band over the sealing PETsleeve (so that the sleeve provides strain relief). Regardless, ports716 will preferably be disposed within corresponding balloon shapes 720and will remain open after the balloon/core assembly 730 is sealedtogether in the straight configuration shown in FIG. 24D. Shape settingof the balloon/core assembly from the straight configuration to thehelically curved configuration of FIG. 24E can be performed by wrappingthe assembly around and/or within a mandrel and heating the wrappedassembly. Helical channels may be included in the mandrel, which mayalso have discrete balloon receptacles or features to help ensurealignment of sets of balloons along the desired lateral balloon axes.Regardless, shape setting of the core/balloon assembly can help set theM different lateral orientations of the balloons, so that the balloonsof each set 720 i, 720 ii, 720 iii are aligned, as seen in 24E-1. Asnoted elsewhere, due to some slight changes in the geometry of thecoiled assembly during axial elongation and the like, there may be someslight circumferential offset between balloons of the same lateralbending orientation when the articulated structure and/or its componentsare in some configurations, including when at rest.

Referring to FIG. 24E-2, an alternative balloon tube 718′ has aplurality of pre-curved balloon shapes 720′ coupled together by sealingzones 722 to facilitate forming and/or keeping the balloon/core assemblyin a helical configuration. The overall configuration of alternativeballoon tube 718′ is straight, and it may be beneficial to provideasymmetric corrugated transitions 725 between pre-curved balloon shapes720′ and sealing zones 722. Corrugated transitions 725 may have a formanalogous to that of a corrugated straw along at least an outer radialportion of the helix, and the balloon shapes may optionally havecorrugations along this outer portion instead of or in addition to thepre-curvature shown schematically here. The balloon shapes, transitions,and sealing zones may be formed by blow molding within machined orprinted tooling using medical balloon blowing techniques, by blowmolding with the moving tooling of a corrugation system, or the like.

Referring to FIG. 24E-3, a detail for an exemplary seal between sealingzone 722 of balloon tube 718 and an outer surface of multi-lumen core702 is illustrated. In some embodiments, bonding 711 of balloon tube 718to core 702 employs adhesives, thermal bonding, laser bonding, or thelike, and is sufficient to inhibit fluid flow between adjacent balloons.Optionally, a band of radially compressive material 713 can be disposedover the balloon tube and core to help maintain sealing engagement whenone or both of the adjacent balloons are inflated. Suitable bands maycomprise metal and may be crimped or swaged onto the assembly, with thebands optionally comprise thin tubular marker bands-like structures(optionally comprising stainless steel, silver, gold, platinum, or thelike) that are swaged on using standard marker band swaging tools andtechniques. Alternative compressive bands may comprise a flexiblefilament of a polymer such as nylon, polyester, spectra, or the like,and may be wound over the balloon tube and core and adhesively bonded.Still further alternative compressive bands may comprise a micro-crimpclamp, or the like. A strain-relief tube 715 (optionally comprising PETor the like) may optionally be provided between band 713 and balloontube 718 to inhibit damage along the edge of the band, and/or the bandmay be flared radially outwardly at the ends. Preferably, the band andany strain relief tube will be compressed onto the balloon so that someor all of the outer surface of the band and strain relief tube arerecessed to near or even below the adjacent balloon tube, analogous towhen a standard marker band is crimped onto a standard catheter tubing.

Referring now to FIGS. 24F and 24G, exemplary inner and outer helicalC-channel frames, 732 and 734 respectively, can be seen. Inner helicalframe 732 and outer helical frame 734 incorporate the modified C-channelframe 680 of FIG. 22a , but with the C-channels defined by axiallycontinuous helical walls 736 with flanges 740 along their proximal anddistal helical edges. The helical flanges are axially engaged by opposedballoons and allow inflation of the balloons to locally axially contractand/or extend the skeleton and catheter (or other articulatable body) ina manner that is analogous to the annular flanges of the ring framesdescribed above. An optional helical nub 742 protrudes axially into thechannel of inner ring frame 734 to allow the frames to pivot againsteach other along a flange/flange engagement, so that the nub couldinstead be included on the flange of the outer frame or on both (or maycomprise a separate structure that is axially sandwiched between theflanges of the two frames). Alternative embodiments may forego such apivotal structure altogether.

Referring now to FIGS. 25A-25D, a segment of an exemplary flexibleextension/contraction helical frame articulation structure 750(sometimes referred to herein as a push/pull helical structure)incorporates the components of FIGS. 24A-24G, and provides thefunctionality of the annular extension/contraction frame embodiments ofFIGS. 22B-22I. Push/pull structure includes a skeleton defined by innerand outer helical frames 732, 734, and also includes three balloon/coreassemblies 730 a, 730 b, and 730 c, respectively. Each balloon/coreassembly includes a set of balloons at three lateral orientations, 720i, 720 ii, and 720 iii. Balloon/core assembly 730 b extends along ahelical space that is axially between a flange of the inner frame and aflange of the outer frame, and that is radially between a wall of theinner frame and a wall of the outer frame, so that the frames overlapalong this balloon/core assembly. Hence, when balloons 720 ofballoon/core assembly 730 inflate, they push the adjacent flanges apartand increase the overlap of the frames, inducing axial contraction ofthe skeleton, such that the balloons of this assembly function ascontraction balloons. In contrast, balloon/core assemblies 730 a and 730c are radially adjacent to only inner frame 732 (in the case of assembly730 a) or outer frame 734 (in the case of assembly 730 b). Expansion ofthe balloons 720 of assemblies 730 a, 730 c pushes axially againstframes so as to decrease the overlap of the frames, and acts inopposition to the inflation of balloons 720 of assembly 730 b. Hence,balloons 720 of assemblies 730 a, 730 c function as extension balloons.

Referring now to FIGS. 25A-25C, when all the contraction balloons 720 ofassembly 730 b are inflated and all the extension balloons of assemblies730 a, 730 c are deflated, the push/pull structure 750 is in a straightshort configuration as shown in FIG. 25A. Even partial inflation of theextension balloons and even partial deflation of the contractionballoons articulates push/pull structure 750 to a straight intermediatelength configuration, and full inflation of all extension balloons ofassemblies 730 a, 730 c (along with deflation of the contractionballoons) fully axially elongates the structure. As with the ringpush/pull frames, inflating contraction balloons 720 ii along onelateral orientation of assembly 730 b (with corresponding deflation ofthe extension balloons 720 ii of assemblies 730 a, 730 b) locallydecreases the axial length of the skeleton along that side, whileselective deflation of contraction balloons 720 i of assembly 730 b(with corresponding inflation of extension balloons 720 i of assemblies730 a and 730 c) locally increases the length of the skeleton, resultingin the fully laterally bent configuration of FIG. 25E. Note thatextension and contraction balloons along the 720 iii orientation may beinflated and deflated with the extension and contraction orientationballoons of orientation 720 ii so as to keep the curvature in the planeof the drawing as shown. Stiffness of the structure may be modulateduniformly or locally (with axial and/or orientation variations) asdescribed above regarding the ring frame embodiments. Similarly, thenumber of extension and contraction balloons along each orientation(which will often be associated with the number of loops of assemblies730 a, 730 b, etc) may be determined to provide the desired range ofmotion, resolution, and response. As described with reference to thepush/pull ring frame embodiments, the overall articulated portion of thestructure will often be separated into a plurality of independentlycontrollable segments.

Referring now to FIG. 25F, push/pull structure 750 will often include anouter flexible sheath 752 and an inner flexible sheath 754. Sheaths 752,754 may be sealed together at a distal seal 756 distal of the inflationlumens and balloons of assemblies 730, and one or more proximal seal(not shown) may be provided proximal of the balloons and/or near aproximal end of the catheter structure, so as to provide a sealed volumesurrounding the articulation balloons. A vacuum can be applied to thissealed volume, and can be monitored to verify that no leaks are presentin the balloons or inflation lumen system within a patient body.

Referring now to FIGS. 26A and 26B, an alternative push/pull structureomits one of the two extension balloon assemblies 730 a, 730 c, and usesa 1-to-1 extension/contraction balloon opposition arrangement asdescribed above with reference to FIGS. 23A and 23B. Note that thisembodiment retains balloon assembly 730 c that is radially adjacent toouter frame 734 (so that no balloons are visible even with the sheathremoved). Alternative embodiments may retain assembly 730 a and foregoassembly 730 c (so that balloons could be seen through a clear sheath,for example).

Referring now to FIG. 27, short segments of alternative core structuresare shown for comparison. Core shaft 702 has an outer diameter of about0.028″ and 7 lumens, with 6 peripheral lumens having an inner diameterof about 0.004″ readily available for formation associated ports and usein transmitting inflation fluid to and from balloons. A central lumenmight be used, for example, in monitoring of the vacuum system to verifyintegrity of the system. Core shaft 702 can be used, for example, in a14-15 Fr catheter system having two segments that are each capable ofproviding up to 120 degrees of bending (or alternatively more or lessdepending on the number of balloons ganged together on each channel),with such a system optionally capable of providing a bend radiussufficient for to fit a 180 degree bend of the catheter within a spaceof 3 inches or less, ideally within 2½ inches or less, and in some caseswithin 2 inches or less. Such a system may be beneficial for structuralheart therapies, for example, and particularly for mitral valvedelivery, positioning, and/or implantation.

Referring still to FIG. 27, other therapies may benefit from smallercatheter profiles, and do not need the bending forces available from a15 Fr catheter. Electrophysilogy therapies such as AFib ablation fromwithin an atrium of the heart may be good examples of therapies whichwould benefit from the degrees of freedom that can be provided in smallstructures using the systems described herein. Scaling the 15 Fr systemdown for a 7-8 Fr ablation catheter might make use of a directly scaledcore 762 having half the overall outer diameter and half the lumen innerdiameter of core 702, as the pressure-containing stresses in thematerial would scale with the lumen diameters. However, there may becost benefits to maintaining minimum lumen wall thicknesses that areabove 0.002″, preferably at or above 0.0025″, and ideally at or aboveabout 0.003″. Toward that end, and to provide 6 contraction or extensionlumens for two 3D push/pull segments along a common helical core alongwith a desirably small bend radius, it may be beneficial to use radiallyelongate core 764 having a 6 lumens that are all surrounded by at least0.003″ of material. Core 764 has an axial height of half of core 702 anda radial width of that is less than half the balloon diameter of the14-15 Fr system. There may be benefits to having the radial (elongate)dimension of the cross-section being less than the inflated innerdiameter of the balloons mounted thereon, to inhibit trapping ofinflation fluid on one axial side of the balloon (away from theinflation port).

Still further advantages may be provided by applying the smaller lumenand wall thickness dimensions of 7 Fr core 762 to a 15 Fr catheter coresize, as it results in the 12 inflation lumen core 766. The large13^(th) lumen of this embodiment may help enhance flexibility of thesegments, and can again be used to monitor system integrity using avacuum system. The 12 lumens may allow, for example, a continuouspush/pull structure to have 4 independently controllable 3D shape (4Dshape+stiffness) segments. A 16 inflation lumen core 768 combines thesmaller lumen and wall thickness with a radially elongate cross-section,allowing 5 independently controllable 3D segments. It should beunderstood that still further numbers of lumens at smaller profiles arepossible using known and relatively low cost multilumen extrusiontechniques.

It should be understood that still further alternative embodiments maytake advantage of the beneficial components and assemblies describedherein. For example, as can be understood from the disclosure aboveregarding many of the flexible structures of FIGS. 3-12, inflation of aballoon may be resiliently opposed by a helical spring or other biasingstructure so that the spring deflates the balloon and urges a flexiblebody back toward a pre-balloon-inflation state when the inflation fluidis released from the balloon. Rather than relying on 6 dedicated opposedexpansion and contraction balloon channels for each segment (providingindependent contraction and expansion along each lateral orientation) inthe push/pull ring frame and push/pull helical frame embodimentsdescribed above, two or more of the channels (from the same segments orfrom different segments) may be grouped together to act as a commonbaising structure or fluid spring. As an example, all the contractionballoons along two adjacent segments might open to a single lumen thatis inflated to less than full pressure. Modulating pressure to thedifferent sets of extension balloons may still allow the extensionballoons to articulate each segment with three independent degrees offreedom, as the grouped contraction balloons could selectively beoverpowered by the extension balloons (like the coil springs) or may beallowed to deflate the extension balloons. In some embodiments, ratherthan relying on partial pressure of extension or contraction balloons,an elastomeric material may be mounted over the core of some or all ofthe extension or contraction balloons of a segment so as to passivelyoppose a set of the balloons.

Referring now to FIG. 28, an articulation controller 770 for directinginflation fluid to and from the actuation balloons of the systems willtypically have hardware and/or software configured and programmed togenerally seek to cause the articulable structure to assume a new actualposition or state X_(actual) in response to a commanded trajectory 772input by a system user. Many of the articulated flexible structuresdescribed herein may be included in robotic systems that can be analyzedand controlled using techniques associated with continuum robots, andthe articulated structures will often be under-constrained with morejoints then can be directly controlled using a standard controller.These excess or redundant degrees of freedom are often managed and madeto cooperate by controller 770 using an internal compliance that directsthe joints to be at a similar angle relative to the next joint withinthe segment. Controller 770 assumes equal joint angles within thesegment for solving control equations. The segment bias (towardsstraight, for example) and strain associated with inducing a bend awayfrom the preferred orientation causes a preference for internal jointsto be at similar relative angles. The processor of the system willtypically have software modules to determine the next desired positionor state of the articulatable structure X_(iDesired), and will applyinverse catheter kinematics 774 to determine the next desired jointstate θ_(iDesired). A difference between an actual joint state and thenext desired joint state is determined to define a joint error, and thedesired joint state can be fed forward to a joint trajectory planner 776along with the joint error to define a joint error trajectory. Thisjoint trajectory can be used in an inverse fluidic calculation 778 todetermine command signals that can be fed into a closed-loop valvecontroller 780 so as to provide an actuated joint state. In someembodiments, closed loop control of the valves may depend on pressuresensing, and may be used to control to specific pressures as determinedby valve inverse kinematics. The catheter dynamics and mechanicsreaction to the actuated joint state (with the associated environmentinteractions with the catheter such as tissue forces and the like)result in a new actual position or state X_(actual) of the articulatedcatheter system.

Feedback on the actual position or state of the articulated system tothe controller may be omitted in some embodiments, but other embodimentsmay benefit from such feedback to provide more precise movements andbetter correlation (from the system user's perspective) between thecommand inputs and the actual changes in state. Toward that end, thecontroller may optionally use one or more closed loop feedback pathways.In some embodiments, a feedback system that is partially or fullyexternal to the articulated structure 782 may sense the actual positionor state of the catheter or other articulated structure using alocalization sensor 784, such as an electromagnetic navigation system,an ultrasound navigation system, image processing coupled to 3D imaging(such as biplanor fluoroscopy, magnetic resonance imaging, computedtomography, ultrasonography, stereoscopic cameras, or the like; wherethe imaging modality may optionally also be used to produce imagespresented to the system user for image guided articulation). In manyembodiments, the feedback will be provided using signals obtained fromthe articulated system itself under an internal closed loop feedbacksystem 786. To obtain a measured shape or state of the articulatedstructure, a variety of known sensor technologies may be employed as anarticulated structure shape sensor 788, including optical fiber shapesensors (such as those using fiber Bragg gratings), electrical shapesensors (such as those which use elastically deformable circuitcomponents), or the like. The measured and/or sensed signals may beprocessed using inverse kinematics to derive associated measure and/orsensed joint states. Furthermore, balloon array pressure signals willoften be available from the pressure sensors of the system, along withinformation correlating the pressures with the joint or shape state ofthe articulated system. The history of inflation fluid directed to andexhausted from the articulation balloons may also be used to helpdetermine an estimated inflation fluid quantity present in each balloon(or set of balloons on a common inflation lumen). Where balloons aremounted in opposition or in parallel, the pressure and inflation fluidquantity of these related balloons on separate channels may also beavailable. Some or all of this pressure information may be processedusing a joint kinematics processor 790 to determine a pressure-derivedjoint position or state (including a derived position of thepressure-articulated joints making up the flexible structure kinematicchain θ_(LDevived)). The pressure information, preferably along withinternal localization information and/or external localizationinformation, may also be used by the joint kinematic processor 790 toderive the loads on the joints, for determining of motion limits 775 asused by the joint trajectory planner 776, and the like. Where more thanone is available, the external localization-based feedback joint state,the internal shape-sensor based joint state, and the pressure-derivedjoint state may be rectified 792 and the rectified (or otherwise anyavailable) joint state compared to the desired joint state to determinethe joint error signal.

Referring now to FIG. 29, an exemplary data processing structure 800 forcontrolling the shape of a catheter or other articulated elongateflexible bodies described herein can be understood. Much of the dataprocessing occurs on a controller board 802 of reusable driver 804, withthe driver optionally comprising a hand-held capital equipment unit. Theinput device 806 may optionally include a separate workstation withwired or wireless data telemetry (so as to allow, for example, aninterventional cardiologist or the like to perform a portion of theprocedure while separated from the radiation field of a fluoroscopysystem), or input device 806 may be a user interface integrated into thehand-held driver, or both. Preferably, the valve manifold 808 willcomprise one of the modular plate manifold structures described herein,and will be contained within the hand-held driver unit 804. Canister 810may be affixed to the driver (directly or by coupling of the catheter tothe driver), and will often be included within a hand-held proximalassembly of deployment system that includes the driver, the proximalinterface of the catheter, and other proximal components of the catheter(such as the heart valve actuation or deployment device 813, or thelike) during use. Similarly, a battery of the system (not shown) may beintegrated into the driver 804, may be mounted to the proximal interfaceof the catheter, or both.

A catheter 812 or other elongate flexible body for use with driver 804will generally have a proximal interface 814 that mates with areceptacle 816 of the driver. As can be understood with reference to thedescriptions above, the mating of the proximal interface with thereceptacle will often provide sealed fluid communication between aballoon array of the catheter and the valves of the manifold assembly.Coupling of the proximal interface with the receptacle may also resultin coupling of electrical contacts of the driver 818 with electricalcontacts of the catheter 820, thereby facilitate access to internalshape sensor data, external localization data (which may employ apowered fiducial on the catheter and an external electromagnetic sensorsystem, or the like). Still further communications between the catheterand the driver may also be facilitated, including transmission ofcatheter identification data (which may include a catheter type forconfiguration of the controller, a unique catheter identifier so as tohelp inhibit undesirable and potentially deleterious re-use of thecatheter, and the like). As an alternative to (or in addition to)electrical communication of this data, catheter 812 may have an RFID,bar code, or other machine-readable tag on or near proximal interface814, and driver 804 may include a corresponding reader one or nearreceptacle 816.

Referring now to FIGS. 30A-30D, an alternative interface 830 disposed atthe proximal end of the catheter can be understood, along with mating ofthat proximal interface of the catheter to an alternative receptacle 832of an alternative modular manifold 834. Proximal interface 830 may bepermanently or removably affixed to the proximal end of the catheter andprovides a quick-disconnect sealed communication between axiallyseparated ports of up to three multi-lumen shafts 836 of the catheter toassociated valves and fluid channels of the manifold. The ports of themulti-lumen shafts can be sealed to proximal interface 830 by axiallycompressing O-rings 838 or other deformable sealing bodies interleavedbetween more rigid interface members 840. Threaded compression members842 maintain axial sealing compression between a proximal-most interfacemember and a distal-most interface member. Posts 844 of interfacemembers 840 extend laterally and parallel to each other. Each interfacemember 840 includes a post 844 for each multi-lumen shaft, and thenumber of interface members included in proximal interface 830 is thesame as the number of independently used lumens in each multi-lumenshaft, so that the posts form an array with the total number of postsbeing equal to the total number of independent multi-lumen channels inthe articulated structure. Lumens extend radially from the ports of themulti-lumen shaft, through the posts 844, and to an interface portsurrounded by a cap of deformable seal material.

Referring to FIG. 30D, receptacle 832 of manifold assembly 834 has aseries of indentations that correspond with posts 844 of proximalinterface 830. The indentations have surfaces that correspond to theposts and seal to the deformable caps with the interface ports each insealed fluid communication with an associated channel of an associatedplate module. In this embodiment, the receptacle surfaces of each platemodules are on a receptacle member 848. The receptacle members supportplate layers with channels formed between the layers, with MEMS valvesand pressure sensors mounted to the plates as described above. Here,however, the plates of adjacent plate modules may not be in directplate-plate contact, so that the supply and exhaust flows may extendaxially through the receptacle members, through the proximal interface,or through another structure of the manifold assembly. As noted above,alternative embodiments may have plates that are in direct contact, withany housings for valves, pressure sensors, and the like formed as voidsbetween layers, and with inflation and/or deflation fluid transmitteddirectly between plate modules through seals (such as O-rings,formed-in-place seals, gasket material affixed to flex circuitstructures, or the like).

Referring now to FIGS. 31A-31E, an alternative balloon-articulatedstructure 850 having a single multi-lumen core may be particularly wellsuited for smaller profile applications, such as for microcathetershaving sizes down to 2 or 3 Fr, guidewires, or the like. Articulatedstructure 850 generally has a proximal end 852 and a distal end 854 andmay define an axis therebetween. A frame 856 of the structure is shownby itself in FIG. 31C and is generally tubular, having a series of loops858 interconnected by axial struts 860. Two struts may be providedbetween each pair of adjacent loops, with those two struts beingcircumferentially offset by about 180 degrees; axially adjacent strutsbetween nearby loop pairs may be offset by about 90 degrees,facilitating lateral bending of the frame in orthogonal lateral bendingorientations. As will be understood from many of the prior framestructures described herein, apposed surface region pairs between loops858 will move closer together and/or farther apart with lateral bendingof frame 850, so that a balloon can be used to control the offsetsbetween these regions and thereby the bending state of the frame.

A multi-lumen core 862 is shown by itself in FIG. 31B, and extendsaxially within the lumen of frame 856 when used (as shown in FIG. 31D).Core 862 includes a plurality of peripheral lumens 864 surrounding acentral lumen 868. Central lumen 868 may be left open as a workingchannel of articulated structure 850, to allow the articulated structureto be advanced over a guidewire, for advancing a guidewire or toolthrough the articulated structure, or the like. An array 870 ofeccentric balloons 872 is distributed axially and circumferentiallyabout the multi-lumen core, with the array again taking the form of anM×N array, with M subsets of balloons being distributedcircumferentially, each of the M subsets being aligned along a lateralbending orientation (M here being 4, with alternative embodiments having1, 2, 3, or other numbers of circumferential subsets as describedabove). Each of the M subsets includes N balloons, with N typicallybeing from 1 to 20. The N balloons of each subset may be in fluidcommunication with an associated peripheral lumen 864 so that they canbe inflated as a group. Eccentric balloons 872 may optionally be formedby drilling ports between selected peripheral lumens 864 to the outersurface of the body of the core, and by affixing a tube of balloon wallmaterial affixed over the drilled body of multi-lumen core 862, with theinner surface of the balloon tube being sealingly affixed to an outersurface of the multi-lumen body of the core. Alternatively, eccentricballoons may be integral with the multi-lumen core structure, forexample, with the balloons being formed by locally heating anappropriate region of the multi-lumen core and pressurizing anunderlying lumen of the core to locally blow the material of themulti-lumen body of the core radially outwardly to form the balloons.Regardless, the balloons extend laterally from the body of themulti-lumen core, with the balloons optionally comprising compliantballoons, semi-compliant balloons, or non-compliant balloons. The shapeof the inflated balloons may be roughly spherical, hemispherical, kidneyshaped (curving circumferentially about the axis of the core),cylindrical (typically with a length:diameter aspect ratio of less than3:1, with the length extending radially or circumferentially), or somecombination of two or more of these.

When multi-lumen core 862 is assembled with frame 856 (as in FIGS. 31A,31C, and 31D), the body of the multi-lumen core is received in the lumenof the frame and balloons 872 are disposed between the apposed surfacesof loops 858. By selectively inflating one subset of balloons 872aligned along one of the lateral bending orientations, and byselectively deflating the opposed subset of balloons (offset from theinflated balloons by about 180 degrees), the axis of articulatablestructure 850 can be curved. Controlling inflation pressures of theopposed balloon subsets may vary both a curvature and a stiffness ofarticulatable structure 850, with increasing opposed inflation pressuresincreasing stiffness and decreasing opposed inflation pressuresdecreasing stiffness. Varying inflation of the laterally offset balloonsets (at 90 and 270 degrees about the axis, for example) may similarlyvariably curve the structure in the orthogonal bending orientation andcontrol stiffness in that direction.

As can be understood with reference to FIG. 31E, the profile of thesingle-core assembly may be quite small, with an exemplary embodimenthaving an outer diameter 874 of frame 856 at about 1.4 mm, an outerdiameter 876 of the body of multi-lumen core 862 of about 0.82 mm, andan inner diameter 878 of the peripheral lumens 864 of about 0.10 mm. Themulti-lumen core body and balloons may comprise polymers, such as any ofthe extrusion or balloons materials described above, and the frame maycomprise a polymer or metal structure, the frame optionally being formedby molding, cutting lateral incisions in a tube of material, 3Dprinting, or the like. Note that the exemplary multi-lumen corestructure includes 8 peripheral lumens while the illustrated segmentmakes use of 4 lumens to articulate the segment in two degrees offreedom; a second segment may be axially coupled with the shown segmentto provide additional degrees of freedom, and more lumens may beprovided when still further segments are to be included.

Referring now to FIGS. 32A and 32B, a still further alternativearticulated structure 880 is shown in curved and straightconfigurations, respectively. Articulated structure 880 includes a frame882 that is optionally formed by cutting lateral slits in tubularmaterial and locally bending the tube wall near the slits inward to formshelves or tabs 884. The cut tubular material may comprise a polymer(optionally a polymer impregnated with a PTFE such as Teflon™), or ametal (such as hypotube or a superelastic alloy such as a Nitinol™alloy). Similar structures may alternatively be formed by 3D printing orthe like. Shelves 884 have surfaces that extend generally transverse tothe tubular axis both proximally and distally of the slits. Balloons 886can be disposed between apposed shelves 884 and can deflect an axis ofarticulated structure 880 laterally, with the balloons optionallyextending eccentrically from a multi-lumen core body as described aboveregarding FIG. 31, having a helical balloon/core winding along thearticulating structure as described above regarding FIG. 24, beingformed by bonding balloon layers to a substrate material as describedabove regarding FIG. 10, and/or the like.

Referring now to FIG. 33A, a balloon piston system 890 may be used toprovide axial articulation between distal components, and/or to providerotation about a distal axis of any of the elongate articulatedstructures described herein. Balloon piston system 890 may employinflation fluid for driving axial and/or rotational movement, with thefluid typically flowing distally along an elongate flexible structurewithin a substrate. Hence, balloon piston system 890 might be used, forexample, with an endoluminal prosthetic delivery system to rotationallyposition an axially asymmetric mitral valve prosthesis in alignment witha mitral valve, to withdraw a sheath proximally from a valve prosthesishaving a self-expanding frame, or the like.

System 890 generally includes a piston in the form of a plate 892affixed to an axially slidable shaft 894 between first and secondballoons 896, 898. Ports through slidable shaft 894 provide fluidcommunication between the balloons and first and second lumens of amulti-lumen supply shaft 900, with the first supply lumen being in fluidcommunication with first balloon 896 and the second lumen being in fluidcommunication with second balloon 898. Differential pressure between thetwo balloons acts on the piston and induces axial motion of slidableshaft 894, which may be used to axially actuate a movable componentmounted to the articulated structure (such as to pull back a sheath froma self-expanding stent or valve prosthesis). Optionally, a lead screw orthread 902 at the distal end of slidable shaft 894 may engage threads ofa corresponding rotatable component 904 (with the component being heldat an axial location by rotational bearing surfaces or the like). Hence,piston system 890 can also be used to provide rotation of a componentmounted to an articulated structure.

Referring now to FIG. 33B, an alternative incremental rotation system910 provides incremental rotation about an axis of a catheter or otherarticulated structure, typically near a distal end of the catheter.Incremental rotation system 910 makes use of one or more pairs ofopposed balloons 912 a, 912 b; 912 a′, 912 b′; . . . , with the balloonspreferably being mounted on one or more multi-lumen core shaft thatextends distally (and optionally that winds proximally and distallybetween some or all of the balloons). The core shaft(s) may take anumber of different paths to rotation system 910, with the core shaft(s)optionally continuing distally from a core shaft of an adjacentarticulated segment, or otherwise extending about the periphery of thecatheter between an inner sheath 914 and an outer sheath 916; or therotation system core shaft may alternatively be included in an innercatheter that extends distally through a working lumen of anotherarticulated catheter (such as a lumen of the inner sheath shown in FIG.25F); or the like. Balloons 912 are generally cylindrical in shape, withthe axes of the balloons extending along the axis of the catheter, andthe pairs of balloons are disposed within an axial channel bordered byaxial ribs 918. Ribs 918 can be affixed to a distal portion of eitherthe inner or outer sheath 914, 916 (here being affixed to the innersheath) and a flange disposed between the balloons of each pair isaffixed to the other (here to the outer sheath).

By alternatingly inflating a first of the opposed balloons of each pair912 a, 912 a′, . . . while the second balloon of the pair 912 b, 912 b′,. . . is deflated; and then allowing the first to deflate while thesecond is inflated, the balloons can rotate the distal portion of outersheath 916 relative to inner sheath 914 about the axis of the catheter922, with the distal portion of outer sheath rotating back-and-forth.The back-and-forth rotation of the outer sheath can be used toincrementally rotate a rotatable sheath 924 by including one or moreone-way clip(s) 926 that extend radially from the outer sheath toresiliently engage an inner surface of the rotatable sheath, with theclips angling circumferentially in the desired direction of rotation.Clips 926 typically have a sharpened outer edge, optionally comprising ametal or a high-strength polymer that allows the rotatable sheath toslide when rotated in the desired direction, but which inhibits movementin the opposed direction. Note that a low-torsional stiffness section orjoint of the outer sheath just proximally of the incrementally rotateddistal portion may facilitate incremental rotation in the desireddirection. More specifically, one or more similar clips mounted to theouter sheath proximally of such as torsional joint (and which alsoengage the rotatable sheath) may be combined with clips 926 distal ofthe joint to help prevent the rotatable sheath from rotating counter tothe desired direction when the distal clips slide along the innersurface of the rotatable sheath during the back-and-forth drive rotation(as can be understood with reference to the analogous use of clips 926proximal and distal of an axially flexible section in the axialincremental movement system of FIG. 34). More pairs of opposed balloonsand associated ribs and flanges may be provided about the axis (such asby having 3 sets at 120 degree centers, 4 sets at 90 degree increments,and so forth) to increase the rotational forces, and/or multipleballoons may be grouped together in series to increase the rotationalincrements (as may be understood with reference to the analogous use ofballoons in series to increase axial movement increments sizes asdescribed below and shown in FIG. 35).

Referring now to FIGS. 34A and 34B, an incremental axial actuationsystem 930 can axially articulate a component at or near the distal endof a flexible articulated structure. For example, axial incrementalsystem 930 can incrementally move a slidable sheath 932 proximally overan outer sheath 934 at a distal end of an articulated catheter or otherarticulated structure so as deploy a self-expanding stent or valve. Across-section through one side of axial incremental system 930 is shownin FIGS. 34A and 34B (the centerline of the catheter and actuationsystem being horizontal and below the figures). In this embodiment, acircumferential flange 936 is affixed to and extends radially outwardlyfrom inner sheath 938 between opposed balloons 940 a, 940 b. The opposedballoons are disposed in a movable channel that is axially bordered bycircumferential ribs 942, and those ribs extend radially inwardly from adistal portion of outer sheath 934. The distal portion of the outersheath is coupled with the rest of the outer sheath by an axiallyflexible section or joint (shown here as a corrugated structure).Alternating inflation and deflation between opposed balloons 940 a, 940b moves the channel and the distal portion of the outer sheath axiallyback-and-forth. Clips 926 disposed between the moving channel and theslidable sheath 932 (and similar clips disposed between the outer sheathproximal of the axial joint and the slidable sheath) help turn the axialback-and-forth motion of the channel to incremental axial movement ofthe slidable sheath in the proximal direction. Note that a similarsystem with clips 926 oriented in the axially opposed direction wouldinstead result in axial movement of the sheath in the distal direction.

Where more axial actuation force is desired than is available from asingle balloon pair, a plurality of opposed balloon pairs may be used inparallel to move the sheath proximally (or in some other desiredactuation). To allow additional balloons, flange 936 and ribs 938 cancomprise annular structures that extend circumferentially normal to theaxis of the catheter (allowing 3 or 4 pairs of opposed balloonsdistributed about the axis at 120 or 90 degree centers, for example.Still larger forces may be provided, however, using advantageous helicalflange and rib structures, each having one or more loops extendingaround the axis of the catheter to provide a desired number of opposedballoon pairs (and their associated axial articulation forces). Notethat to provide additional load capability, flange 936 and ribs 938 mayact as rigid bodies (such as by affixing flange 936 to either the inneror outer sheath throughout the helical length of the flange, andaffixing ribs to the other throughout their lengths). Such opposedballoons may be mounted on first and second multi-lumen cores within themovable helical channel. Conveniently, a vacuum chamber may surround theballoons as described above, and the cores may extend distally from thedistal-most lateral and/or axial articulation segment of any of theother articulation systems described herein, through a lumen of an innersheath of one of the articulated structures described herein, or thelike. The axial actuation balloons may optionally be the same size andshape as the articulation balloons, with one lumen of each core beingused for the incremental axial actuation.

Referring now to FIGS. 35A and 35B, yet another incremental axialactuation system illustrates optional components which may addadditional stroke and/or axially reversing capabilities. In thisembodiment, much of the system operates as generally described aboveregarding FIG. 34, but a plurality of opposed balloons 940 a, 940 a′;940 b, 940 b′ . . . are used in series to provide a larger axialmovement increment with each inflation/deflation cycle. Additionally,rather than relying on one-way clips to transform a back-and-forthmotion to an incremental motion in a single desired direction, thissystem includes a simple clutch 944 that can be actuated by inflation ofa clutch engagement balloon 946 so as to axially couple the drivechannel to axially slidable sheath 932. A passive spring or a clutchdisengagement balloon 948 disengages the drive channel from slidablesheath 932, with the clutch here comprising axially opposed edges orother features that that pivot or otherwise move into and out ofengagement with the axially slidable sheath when the clutch is engaged.By appropriate sequencing of clutch engagement, disengagement, proximalmotion of the drive channel, and distal motion of the drive channel,slidable sheath 932 may be moved, for example, first proximally by adesired total amount, and then distally by the same or a differentamount, all in a single procedure. Such movement may help, for example,to recapture and reposition a partially deployed heart valve, and toredeploy the heart valve at an alternative position. When using one-wayclips instead of a clutch, recapture of a partially deployed heart valvemay alternatively be performed by advancing a recapture sheath distallyover the catheter body, axially slidable sheath 932, and the partiallydeployed heart valve frame.

Additional benefits may be available using the devices and systemsdescribed herein. For example, partial inflation of articulationballoons may locally decrease a lateral stiffness of the catheter so asto tailor a pushability and/or trackability of the catheter for aparticular body lumen. Trackability, pushability, torqueability, andcrossability of are known characteristics of catheters which may bequantitatively determined subjectively (by asking a number of users torate the catheters for one or more of these characteristics),empirically (by measuring movement inputs and outputs in a controlledtest), and/or analytically (by modelling interaction of the catheter andresulting catheter performance based on characteristics or properties ofthe catheter structure). Pushability generally reflects the ability of adistal end of the catheter to advance distally within a bending lumen inresponse to an axial insertion performed from proximally of the lumen,while trackability generally reflects the ability of the distal end ofthe catheter to follow a path through a bending lumen (optionally asdefined by a guidewire or the luminal wall) in response to axialinsertion. Both pushability and trackability can vary with a number ofdifferent characteristics of the catheter structure (both oftenimproving with increased outer lubricity, for example), but in at leastsome circumstances they may contradict each other. For example,pushability may be enhanced by increasing an axial stiffness of at leastan axial segment of a catheter, while trackability may be enhanced bydecreasing that axial stiffness. The fluid articulated cathetersdescribed herein may help overcome this challenge for a particular bodylumen, because the axial stiffness of the catheter segments can beindependently varied by varying balloon pressure, optionally withoutapplying pressure so as to impose lateral bends in any particulardirection (absent environmental forces against the catheter).

In one example, good overall pushability and trackability of thecatheter may benefit from a catheter structure with high lateralflexibility (low stiffness) along a distal catheter segment, and arelatively high stiffness (low flexibility) along an intermediate andproximal catheter segments. As the catheter advances distally,trackability may benefit from increasing the flexibility of the distalsegment, while pushability and trackability may overall benefit bydecreasing the stiffness of proximal segment (as it approaches orreaches a bend), and increasing the stiffness of the intermediatesegment (as it leaves the bend and/or extends along a straight section.Catheter segments approaching or along greater curvature may be madeless stiff (often by partial balloon inflation, or by partial deflationof opposed balloons), and so that catheter segments approaching or alongstraighter path portions are more stiff (such as by compete deflation orinflation of the balloons of those segments, or by increasing inflationpressure of opposed balloons).

While the exemplary embodiment have been described in some detail forclarity of understanding and by way of example, a variety ofmodifications, changes, and adaptations of the structures and methodsdescribed herein will be obvious to those of skill in the art. Hence,the scope of the present invention is limited solely by the claimsattached hereto.

1.-14. (canceled)
 15. An articulatable structure comprising: an elongateflexible body having a proximal end and a distal end with an axistherebetween; a plurality of balloons disposed along the body, theballoons inflatable from a first configuration to a second configurationsuch that the balloons alter a bend state of the body; and a flexiblesheath disposed around the balloons, the sheath sealed so as to form apressure chamber with the balloons disposed therein.
 16. Thearticulatable structure of claim 15, wherein the elongate body comprisesa catheter body, the distal end being configured for insertion into apatient, and wherein the chamber flexes laterally with the catheterbody.
 17. The articulatable structure of claim 15, further comprising apressure sensing lumen in fluid communication with the chamber, thepressure sensing lumen extending toward the proximal end.
 18. Thearticulatable structure of claim 17, wherein the balloons are mounted ona substrate, and wherein the substrate has a plurality of lumens forinflating the balloons, the pressure sensing lumen being disposed in thesubstrate.
 19. The articulatable structure of claim 15, wherein thesubstrate comprises a multi-lumen shaft, the balloons having balloonwalls extending around the shaft.
 20. The articulatable structure ofclaim 15, further comprising a vacuum source in fluid communication withthe chamber so as to reduce a pressure of the chamber, the chambercomprising a vacuum chamber.
 21. The articulation structure of claim 20,further comprising a fluid control system having a sensor coupled withthe chamber and a shut-off valve disposed between an inflation fluidsource and the balloons, wherein the shut-off valve inhibits inflationfluid flow to the balloons in response to signals from the sensorassociated with a leak of the inflation fluid.
 22. The articulationstructure of claim 15, wherein the inflation fluid comprises a gas whendisposed in the balloons for use.
 23. A method comprising: inflating aplurality of balloons disposed along an elongate flexible body from afirst configuration to a second configuration such that the balloonsalter a bend state of the body; and flexing a sheath disposed around theballoons with lateral flexing of the body, the sheath sealed so as toform a pressure chamber with the balloons disposed therein.
 24. Anstructure comprising: an elongate flexible skeleton having a proximalend and a distal end with an axis therebetween, the skeleton having aplurality of pairs of interface regions distributed along the axis, thepairs of interface regions defining offsets that vary with flexing ofthe skeleton; an array of balloons operatively coupled with the offsetsof the skeleton such that inflation of at least some of the balloonsalters a lateral bending stiffness of the skeleton.
 25. The structure ofclaim 24, wherein the skeleton has a first axial segment and a secondaxial segment and wherein the pairs of offsets are distributed axiallyalong the first and second axial segments, and wherein selectivelyaltering inflation of a first subset of the balloons disposed along thefirst segment can inhibit changes to the offsets along the first segmentso as to selectively increase a lateral bending stiffness of the firstsegment.
 26. The structure of claim 24, wherein the skeleton has a firstlateral bending orientation and a second lateral bending orientation,and wherein the pairs of offsets are distributed circumferentially alongthe first and second lateral bending orientations, and whereindecreasing inflation of a first subset of the balloons disposed alongthe first lateral bending orientation can facilitate changes to theoffsets along the first lateral bending orientation so as to selectivelydecrease a lateral bending stiffness in the first lateral bendingorientation.
 27. The structure of claim 26, wherein the skeleton has afirst axial segment and a second axial segment and wherein the pairs ofoffsets are distributed axially along the first and second axialsegments, and wherein selectively altering inflation of a third subsetof the balloons disposed along the first segment can inhibit changes tothe offsets along the first segment so as to selectively increase alateral bending stiffness of the first segment.
 28. The structure ofclaim 27, wherein decreasing an inflation pressure of a first subset ofballoons increases a lateral bending stiffness of the skeleton, theskeleton being biased to a straight configuration, and the first subsetof balloons being disposed between the interface regions of the pairsalong the first segment.
 29. The structure of claim 28, wherein theskeleton comprises a helical coil having a plurality of loops, the pairsof interface regions comprising apposed surfaces of the adjacent loops,the first subset of balloons comprising balloon walls disposed betweenthe apposed surfaces, the loops biased to compress and deflate theballoons, axial forces being transmitted between loops by solidmaterials when the balloons are fully deflated so as to provide a firstlateral stiffness, axial forces being transmitted by fluid pressurewithin the balloons when the balloons are partially inflated so as toprovide a second lateral stiffness lower than the first lateralstiffness.
 30. The structure of claim 24, wherein increasing aninflation pressure of a first subset of balloons increases a lateralbending stiffness of the skeleton.
 31. The structure of claim 30,wherein the interface regions of the pair are oriented radially, whereinthe first subset of balloons span the pairs of interface surfaces andradially engage the interface surfaces when the first subset of balloonsare inflated from a first configuration to a second configuration, thefluid pressure of the inflated balloons urging the inflated balloonsagainst the interface regions so as to inhibit changes in the associatedoffsets.
 32. The structure of claim 30, wherein the first subset ofballoons comprises a pair of opposed balloons disposed in a channel ofthe skeleton with a flange of the skeleton therebetween, the offsetscomprising separations between apposed surfaces of the flange and thechannel, increasing inflation pressure of the apposed balloonsincreasing a stiffness of the flange within the channel.
 33. Thestructure of claim 32, wherein the flange and the channel comprisehelical structures engaged by a plurality of opposed pairs of balloons,and wherein the offsets extend primarily axially and anglecircumferentially.
 34. A method comprising: inflation of at least someballoons included in an array of balloons, the array supported by anelongate flexible skeleton, the skeleton having a plurality of pairs ofinterface regions distributed along an axis of the skeleton, the pairsof interface regions defining offsets that vary with flexing of theskeleton, the at least some balloons operatively coupled with theoffsets of the skeleton such that the inflation of the balloons alters alateral bending stiffness of the skeleton.
 35. A catheter comprising: ahelical skeleton structure having a proximal end, a distal end, and anaxis therebetween, the distal end configured for insertion into apatient; an array of balloons supported by the helical skeleton, thearray comprising balloons distributed axially and circumferentiallyabout the skeleton; and a fluid supply system in fluid communicationwith the balloons and configured to selectively inflate any of aplurality of subsets of the balloons so as to selectively alter a shapeand/or stiffness of the helical skeleton.
 36. A catheter as in claim 35,further comprising a passive flexible proximal catheter body portiondisposed between the proximal end and the balloons, wherein the fluidsupply system comprises channels extending along the proximal bodyportion.
 37. A method comprising: selectively inflating a first subsetof balloons, the balloons included in an array of balloons supported bya helical skeleton, the array distributed axially and circumferentiallyabout the skeleton, the inflation of the first subset inducing a firstchange in the shape and/or stiffness of the helical skeleton;selectively inflating a second subset of the balloons, the inflation ofthe second subset inducing a second change in the shape and/or stiffnessof the helical skeleton, the second change in shape and/or stiffnessoffset axially and/or circumferentially from the first change. 38.-59.(canceled)